The 100 most-cited articles in Physical review. D/Physical review. D., 2016

The authors study in detail the quantum mechanical model of $N$ Majorana fermions with random interactions of a few fermions at a time (Sachdev-Ye-Kitaev model) in the large $N$ limit. At low energies, the system is strongly interacting and an emergent conformal symmetry develops. Performing technical calculations, the authors elucidate a number of properties of the model near the conformal point.

Parton distribution functions (PDFs) are crucial ingredients for the calculation of the relevant cross sections for various scattering processes at the Large Hadron Collider (LHC). Including data from several previous experiments, the authors find new PDFs, which will be important for the data analysis at the LHC Run-2.

We present a new frequency-domain phenomenological model of the gravitational-wave signal from the inspiral, merger and ringdown of nonprecessing (aligned-spin) black-hole binaries. The model is calibrated to 19 hybrid effective-one-body--numerical-relativity waveforms up to mass ratios of $1\ensuremath{\mathbin:}18$ and black-hole spins of $|a/m|\ensuremath{\sim}0.85$ (0.98 for equal-mass systems). The inspiral part of the model consists of an extension of frequency-domain post-Newtonian expressions, using higher-order terms fit to the hybrids. The merger ringdown is based on a phenomenological ansatz that has been significantly improved over previous models. The model exhibits mismatches of typically less than 1% against all 19 calibration hybrids and an additional 29 verification hybrids, which provide strong evidence that, over the calibration region, the model is sufficiently accurate for all relevant gravitational-wave astronomy applications with the Advanced LIGO and Virgo detectors. Beyond the calibration region the model produces physically reasonable results, although we…

The possibility that the dark matter comprises primordial black holes (PBHs) is considered, with particular emphasis on the currently allowed mass windows at $1{0}^{16}--1{0}^{17}\text{ }\text{ }\mathrm{g}$, $1{0}^{20}--1{0}^{24}\text{ }\text{ }\mathrm{g}$ and $1--1{0}^{3}{M}_{\ensuremath{\bigodot}}$. The Planck mass relics of smaller evaporating PBHs are also considered. All relevant constraints (lensing, dynamical, large-scale structure and accretion) are reviewed and various effects necessary for a precise calculation of the PBH abundance (non-Gaussianity, nonsphericity, critical collapse and merging) are accounted for. It is difficult to put all the dark matter in PBHs if their mass function is monochromatic but this is still possible if the mass function is extended, as expected in many scenarios. A novel procedure for confronting observational constraints with an extended PBH mass spectrum is therefore introduced. This applies for arbitrary constraints and a wide range of PBH formation models and allows us to identify which model-independent conclusions can be drawn from…

In this paper we discuss the anatomy of frequency-domain gravitational-wave signals from nonprecessing black-hole coalescences with the goal of constructing accurate phenomenological waveform models. We first present new numerical-relativity simulations for mass ratios up to 18, including spins. From a comparison of different post-Newtonian approximants with numerical-relativity data we select the uncalibrated SEOBNRv2 model as the most appropriate for the purpose of constructing hybrid post-Newtonian/numerical-relativity waveforms, and we discuss how we prepare time-domain and frequency-domain hybrid data sets. We then use our data together with results in the literature to calibrate simple explicit expressions for the final spin and radiated energy. Equipped with our prediction for the final state we then develop a simple and accurate merger-ringdown model based on modified Lorentzians in the gravitational-wave amplitude and phase, and we discuss a simple method to represent the low frequency signal augmenting the TaylorF2 post-Newtonian approximant with terms corresponding to…

The recent gravitational wave observations GW150914 and GW151226 reported by the LIGO and Virgo collaborations confirmed a key prediction of general relativity (GR). In this recent Physical Review D paper, the authors ask whether these events are also compatible with a variety of modifications of GR and alternative theories of gravity. In this wide-ranging and thorough study, the authors find that the recent observations put severe constraints on these non-standard theories.

Our earlier paper ``Complexity Equals Action'' conjectured that the quantum computational complexity of a holographic state is given by the classical action of a region in the bulk (the ``Wheeler-DeWitt'' patch). We provide calculations for the results quoted in that paper, explain how it fits into a broader (tensor) network of ideas, and elaborate on the hypothesis that black holes are the fastest computers in nature.

The recent discovery of GW150914, the binary black hole merger detected by Advanced LIGO, has the potential to revolutionize observational astrophysics. But to fully utilize this new window into the Universe, we must compare these new observations to detailed models of binary black hole formation throughout cosmic time. Expanding upon our previous work [C. L. Rodriguez, M. Morscher, B. Pattabiraman, S. Chatterjee, C.-J. Haster, and F. A. Rasio, Phys. Rev. Lett. 115, 051101 (2015).], we study merging binary black holes formed in globular clusters using our Monte Carlo approach to stellar dynamics. We have created a new set of 52 cluster models with different masses, metallicities, and radii to fully characterize the binary black hole merger rate. These models include all the relevant dynamical processes (such as two-body relaxation, strong encounters, and three-body binary formation) and agree well with detailed direct $N$-body simulations. In addition, we have enhanced our stellar evolution algorithms with updated metallicity-dependent stellar wind and supernova prescriptions,…

Gravitational waves from binary coalescences provide one of the cleanest signatures of the nature of compact objects. It has been recently argued that the postmerger ringdown waveform of exotic ultracompact objects is initially identical to that of a black hole, and that putative corrections at the horizon scale will appear as secondary pulses after the main burst of radiation. Here we extend this analysis in three important directions: (i) we show that this result applies to a large class of exotic compact objects with a photon sphere for generic orbits in the test-particle limit; (ii) we investigate the late-time ringdown in more detail, showing that it is universally characterized by a modulated and distorted train of ``echoes''of the modes of vibration associated with the photon sphere; (iii) we study for the first time equal-mass, head-on collisions of two ultracompact boson stars and compare their gravitational-wave signal to that produced by a pair of black holes. If the initial objects are compact enough as to mimic a binary black-hole collision up to the merger, the final…

We present the new nCTEQ15 set of nuclear parton distribution functions (PDFs) with uncertainties. This fit extends the CTEQ proton PDFs to include the nuclear dependence using data on nuclei all the way up to $^{208}\mathrm{Pb}$. The uncertainties are determined using the Hessian method with an optimal rescaling of the eigenvectors to accurately represent the uncertainties for the chosen tolerance criteria. In addition to the deep inelastic scattering and Drell-Yan processes, we also include inclusive pion production data from the Relativistic Heavy Ion Collider to help constrain the nuclear gluon PDF. Furthermore, we investigate the correlation of the data sets with specific nuclear PDF flavor components and asses the impact of individual experiments. We also provide comparisons of the nCTEQ15 set with recent fits from other groups.

The recent announcement by LIGO of the detection of the gravitational-wave signal GW150914 has ignited tremendous interest. The two manuscripts highlighted here detail the impressive analysis performed by LIGO to identify a specific black hole binary merger as the source of GW150914. The papers describe two independent methods of analysis: the matching of the signal to numerical-relativity-generated templates and unmodeled burst analyses. The two papers together provide detailed and virtually incontrovertible evidence, by the standards of experimental physics, of the detection of gravitational waves generated by a merger of a black hole binary system consisting initially of black holes of approximately 36 and 29 solar masses.

We compare the science capabilities of different eLISA mission designs, including four-link (two-arm) and six-link (three-arm) configurations with different arm lengths, low-frequency noise sensitivities and mission durations. For each of these configurations we consider a few representative massive black hole formation scenarios. These scenarios are chosen to explore two physical mechanisms that greatly affect eLISA rates, namely (i) black hole seeding, and (ii) the delays between the merger of two galaxies and the merger of the black holes hosted by those galaxies. We assess the eLISA parameter estimation accuracy using a Fisher matrix analysis with spin-precessing, inspiral-only waveforms. We quantify the information present in the merger and ringdown by rescaling the inspiral-only Fisher matrix estimates using the signal-to-noise ratio from nonprecessing inspiral-merger-ringdown phenomenological waveforms, and from a reduced set of precessing numerical relativity/post-Newtonian hybrid waveforms. We find that all of the eLISA configurations considered in our study should detect…

The Laser Interferometer Gravitational Wave Observatory (LIGO) consists of two widely separated 4 km laser interferometers designed to detect gravitational waves from distant astrophysical sources in the frequency range from 10 Hz to 10 kHz. The first observation run of the Advanced LIGO detectors started in September 2015 and ended in January 2016. A strain sensitivity of better than ${10}^{\ensuremath{-}23}/\sqrt{\mathrm{Hz}}$ was achieved around 100 Hz. Understanding both the fundamental and the technical noise sources was critical for increasing the astrophysical strain sensitivity. The average distance at which coalescing binary black hole systems with individual masses of $30\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ could be detected above a signal-to-noise ratio (SNR) of 8 was 1.3 Gpc, and the range for binary neutron star inspirals was about 75 Mpc. With respect to the initial detectors, the observable volume of the Universe increased by a factor 69 and 43, respectively. These improvements helped Advanced LIGO to detect the gravitational wave signal from the binary black…

Recent measurements of the cosmic microwave background (CMB) anisotropies by Planck provide a sensitive probe of dark matter annihilation during the cosmic dark ages, and specifically constrain the annihilation parameter ${f}_{\mathrm{eff}}⟨\ensuremath{\sigma}v⟩/{m}_{\ensuremath{\chi}}$. Using new results (paper II) for the ionization produced by particles injected at arbitrary energies, we calculate and provide ${f}_{\mathrm{eff}}$ values for photons and ${e}^{+}{e}^{\ensuremath{-}}$ pairs injected at keV-TeV energies; the ${f}_{\mathrm{eff}}$ value for any dark matter model can be obtained straightforwardly by weighting these results by the spectrum of annihilation products. This result allows the sensitive and robust constraints on dark matter annihilation presented by the Planck collaboration to be applied to arbitrary dark matter models with $s$-wave annihilation. We demonstrate the validity of this approach using principal component analysis. As an example, we integrate over the spectrum of annihilation products for a range of Standard Model final states to determine the CMB…

We calculate the production of a massive vector boson by quantum fluctuations during inflation. This gives a novel dark-matter production mechanism quite distinct from misalignment or thermal production. While scalars and tensors are typically produced with a nearly scale-invariant spectrum, surprisingly the vector is produced with a power spectrum peaked at intermediate wavelengths. Thus dangerous, long-wavelength, isocurvature perturbations are suppressed. Further, at long wavelengths the vector inherits the usual adiabatic, nearly scale-invariant perturbations of the inflaton, allowing it to be a good dark-matter candidate. The final abundance can be calculated precisely from the mass and the Hubble scale of inflation, ${H}_{I}$. Saturating the dark-matter abundance we find a prediction for the mass $m\ensuremath{\approx}{10}^{\ensuremath{-}5}\text{ }\text{ }\mathrm{eV}\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0ex}{0ex}}({10}^{14}\text{ }\text{ }\mathrm{GeV}/{H}_{I}{)}^{4}$. High-scale inflation, potentially observable in the cosmic microwave background, motivates an…

We present a method for detection and reconstruction of the gravitational wave (GW) transients with the networks of advanced detectors. Originally designed to search for transients with the initial GW detectors, it uses significantly improved algorithms, which enhance both the low-latency searches with rapid localization of GW events for the electromagnetic follow-up and high confidence detection of a broad range of the transient GW sources. In this paper, we present the analytic framework of the method. Following a short description of the core analysis algorithms, we introduce a novel approach to the reconstruction of the GW polarization from a pattern of detector responses to a GW signal. This polarization pattern is a unique signature of an arbitrary GW signal that can be measured independently from the other source parameters. The polarization measurements enable rapid reconstruction of the GW waveforms, sky localization, and helps identification of the source origin.

We present a general procedure for constructing exact black hole solutions with electric or magnetic charges in general relativity coupled to a nonlinear electrodynamics. We obtain a variety of two-parameter family spherically symmetric black hole solutions. In particular, the singularity at the center of the space-time can be canceled in the parameter space and the black hole solutions become regular everywhere in space-time. We study the global properties of the solutions and derive the first law of thermodynamics. We also generalize the procedure to include a cosmological constant and construct regular black hole solutions that are asymptotic to anti--de Sitter space-time.

Within the next few years, Advanced LIGO and Virgo should detect gravitational waves from binary neutron star and neutron star-black hole mergers. These sources are also predicted to power a broad array of electromagnetic transients. Because the electromagnetic signatures can be faint and fade rapidly, observing them hinges on rapidly inferring the sky location from the gravitational-wave observations. Markov chain Monte Carlo methods for gravitational-wave parameter estimation can take hours or more. We introduce BAYESTAR, a rapid, Bayesian, non-Markov chain Monte Carlo sky localization algorithm that takes just seconds to produce probability sky maps that are comparable in accuracy to the full analysis. Prompt localizations from BAYESTAR will make it possible to search electromagnetic counterparts of compact binary mergers.

We study the shadows cast by the different types of rotating regular black holes viz. Ay\'on-Beato-Garc\'{\i}a (ABG), Hayward, and Bardeen. These black holes have in addition to the total mass ($M$) and rotation parameter ($a$), different parameters as electric charge ($Q$), deviation parameter ($g$), and magnetic charge (${g}_{*}$). Interestingly, the size of the shadow is affected by these parameters in addition to the rotation parameter. We found that the radius of the shadow in each case decreases monotonically, and the distortion parameter increases when the values of these parameters increase. A comparison with the standard Kerr case is also investigated. We have also studied the influence of the plasma environment around regular black holes to discuss its shadow. The presence of the plasma affects the apparent size of the regular black hole's shadow to be increased due to two effects: (i) gravitational redshift of the photons and (ii) radial dependence of plasma density.

We propose a space-based gravitational wave (GW) detector consisting of two spatially separated, drag-free satellites sharing ultrastable optical laser light over a single baseline. Each satellite contains an optical lattice atomic clock, which serves as a sensitive, narrowband detector of the local frequency of the shared laser light. A synchronized two-clock comparison between the satellites will be sensitive to the effective Doppler shifts induced by incident GWs at a level competitive with other proposed space-based GW detectors, while providing complementary features. The detected signal is a differential frequency shift of the shared laser light due to the relative velocity of the satellites, and the detection window can be tuned through the control sequence applied to the atoms' internal states. This scheme enables the detection of GWs from continuous, spectrally narrow sources, such as compact binary inspirals, with frequencies ranging from $\ensuremath{\sim}3\text{ }\text{ }\mathrm{mHz}--10\text{ }\text{ }\mathrm{Hz}$ without loss of sensitivity, thereby bridging the…

Precise measurements of the cosmic microwave background (CMB) power spectrum are in excellent agreement with the predictions of the standard $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ cosmological model. However, there is some tension between the value of the Hubble parameter ${H}_{0}$ inferred from the CMB and that inferred from observations of the Universe at lower redshifts, and the unusually small value of the dark-energy density is a puzzling ingredient of the model. In this paper, we explore a scenario with a new exotic energy density that behaves like a cosmological constant at early times and then decays quickly at some critical redshift ${z}_{c}$. An exotic energy density like this is motivated by some string-axiverse-inspired scenarios for dark energy. By increasing the expansion rate at early times, the very precisely determined angular scale of the sound horizon at decoupling can be preserved with a larger Hubble constant. We find, however, that the Planck temperature power spectrum tightly constrains the magnitude of the early dark-energy density and thus any shift in…

We discuss static spherically symmetric metrics which represent nonsingular black holes in four- and higher-dimensional spacetime. We impose a set of restrictions, such as a regularity of the metric at the center $r=0$ and Schwarzschild asymptotic behavior at large $r$. We assume that the metric besides mass $M$ contains an additional parameter $\ensuremath{\ell}$, which determines the scale where modification of the solution of the Einstein equations becomes significant. We require that the modified metric obeys the limiting curvature condition; that is, its curvature is uniformly restricted by the value $\ensuremath{\sim}{\ensuremath{\ell}}^{\ensuremath{-}2}$. We also make a ``more technical'' assumption that the metric coefficients are rational functions of $r$. In particular, the invariant $(\ensuremath{\nabla}r{)}^{2}$ has the form ${P}_{n}(r)/{\stackrel{\texttildelow{}}{P}}_{n}(r)$, where ${P}_{n}$ and ${\stackrel{\texttildelow{}}{P}}_{n}$ are polynomials of the order of $n$. We discuss first the case of four dimensions. We show that when $n\ensuremath{\le}2$ such a metric…

We report a measurement of the ratio $\mathcal{R}({D}^{*})=\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{*+}{\ensuremath{\tau}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}})/\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{*+}{\ensuremath{\ell}}^{\ensuremath{-}}{\overline{\ensuremath{\nu}}}_{\ensuremath{\ell}})$, where $\ensuremath{\ell}$ denotes an electron or a muon. The results are based on a data sample containing $772\ifmmode\times\else\texttimes\fi{}1{0}^{6}\text{ }\text{ }B\overline{B}$ pairs recorded at the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance with the Belle detector at the KEKB ${e}^{+}{e}^{\ensuremath{-}}$ collider. We select a sample of ${B}^{0}{\overline{B}}^{0}$ pairs by reconstructing both $B$ mesons in semileptonic decays to ${D}^{*\ensuremath{\mp}}{\ensuremath{\ell}}^{\ifmmode\pm\else\textpm\fi{}}$. We measure $\mathcal{R}({D}^{*})=0.302\ifmmode\pm\else\textpm\fi{}0.030(\text{stat})\ifmmode\pm\else\textpm\fi{}0.011(\text{syst})$, which is within $1.6\ensuremath{\sigma}$ of the Standard Model theoretical…

We present results for several light hadronic quantities (${f}_{\ensuremath{\pi}}$, ${f}_{K}$, ${B}_{K}$, ${m}_{ud}$, ${m}_{s}$, ${t}_{0}^{1/2}$, ${w}_{0}$) obtained from simulations of $2+1$ flavor domain wall lattice QCD with large physical volumes and nearly physical pion masses at two lattice spacings. We perform a short, $\mathcal{O}(3)%$, extrapolation in pion mass to the physical values by combining our new data in a simultaneous chiral/continuum ``global fit'' with a number of other ensembles with heavier pion masses. We use the physical values of ${m}_{\ensuremath{\pi}}$, ${m}_{K}$ and ${m}_{\mathrm{\ensuremath{\Omega}}}$ to determine the two quark masses and the scale---all other quantities are outputs from our simulations. We obtain results with subpercent statistical errors and negligible chiral and finite-volume systematics for these light hadronic quantities, including ${f}_{\ensuremath{\pi}}=130.2(9)\text{ }\text{ }\mathrm{MeV}$; ${f}_{K}=155.5(8)\text{ }\text{ }\mathrm{MeV}$; the average up/down quark mass and strange quark mass in the $\overline{\mathrm{MS}}$ scheme…

The present paper provides a complete treatment of boundary terms in general relativity to include cases with lightlike boundary segments along with the usual spacelike and timelike ones. Applications of this exhaustive treatment includes a recent conjecture on computational complexity in the context of AdS/CFT.

A novel approach to the effective-one-body description of gravitationally interacting two-body systems is introduced. This approach is based on the post-Minkowskian approximation scheme (perturbation theory in $G$, without assuming small velocities) and employs a new dictionary focussing on the functional dependence of the scattering angle on the total energy and the total angular momentum of the system. Using this approach, we prove to all orders in $v/c$ two results that were previously known to hold only to a limited post-Newtonian accuracy: (i) the relativistic gravitational dynamics of a two-body system is equivalent, at first post-Minkowskian order, to the relativistic dynamics of an effective test particle moving in a Schwarzschild metric, and (ii) this equivalence requires the existence of an exactly quadratic map between the real (relativistic) two-body energy and the (relativistic) energy of the effective particle. The same energy map is also shown to apply to the effective-one-body description of two masses interacting via tensor-scalar gravity.

Collaborative international efforts under the name of the Event Horizon Telescope project, using sub-mm very long baseline interferometry, are soon expected to provide the first images of the shadow cast by the candidate supermassive black hole in our Galactic center, Sagittarius A*. Observations of this shadow would provide direct evidence of the existence of astrophysical black holes. Although it is expected that astrophysical black holes are described by the axisymmetric Kerr solution, there also exist many other black hole solutions, both in general relativity and in other theories of gravity, which cannot presently be ruled out. To this end, we present calculations of black hole shadow images from various metric theories of gravity as described by our recent work on a general parametrization of axisymmetric black holes [R. Konoplya, L. Rezzolla, and A. Zhidenko, Phys. Rev. D 93, 064015 (2016).]. An algorithm to perform general ray-tracing calculations for any metric theory of gravity is first outlined and then employed to demonstrate that even for extremal metric deformation…

We consider all degenerate scalar-tensor theories that depend quadratically on second-order derivatives of a scalar field, which we have identified in a previous work. These theories, whose degeneracy, in general, ensures the absence of Ostrogradsky's instability, include the quartic Horndeski Lagrangian and its quartic extension beyond Horndeski, as well as other Lagrangians. We study how all these theories transform under general disformal transformations and find that they can be separated into three main classes that are stable under these transformations. This leads to a complete classification modulo disformal transformations. Finally, we show that these higher order theories include mimetic gravity and some particular khronometric theories. They also contain theories that do not correspond, to our knowledge, to already studied theories, even up to disformal transformations.

We propose a universal inequality that unifies the Bousso bound with the classical focusing theorem. Given a surface $\ensuremath{\sigma}$ that need not lie on a horizon, we define a finite generalized entropy ${S}_{\mathrm{gen}}$ as the area of $\ensuremath{\sigma}$ in Planck units, plus the von Neumann entropy of its exterior. Given a null congruence $N$ orthogonal to $\ensuremath{\sigma}$, the rate of change of ${S}_{\mathrm{gen}}$ per unit area defines a quantum expansion. We conjecture that the quantum expansion cannot increase along $N$. This extends the notion of universal focusing to cases where quantum matter may violate the null energy condition. Integrating the conjecture yields a precise version of the Strominger-Thompson quantum Bousso bound. Applied to locally parallel light-rays, the conjecture implies a novel inequality, the quantum null energy condition, a lower bound on the stress tensor in terms of the second derivative of the von Neumann entropy. We sketch a proof of the latter relation in quantum field theory.

We study spectral and thermodynamic properties of the Sachdev-Ye-Kitaev model, a variant of the $k$-body embedded random ensembles studied for several decades in the context of nuclear physics and quantum chaos. We show analytically that the fourth- and sixth-order energy cumulants vanish in the limit of a large number of particles $N\ensuremath{\rightarrow}\ensuremath{\infty}$, which is consistent with a Gaussian spectral density. However, for finite $N$, the tail of the average spectral density is well approximated by a semicircle law. The specific heat coefficient, determined numerically from the low-temperature behavior of the partition function, is consistent with the value obtained by previous analytical calculations. For energy scales of the order of the mean level spacing we show that level statistics are well described by random matrix theory. Due to the underlying Clifford algebra of the model, the universality class of the spectral correlations depends on $N$. For larger energy separations we identify an energy scale that grows with $N$, reminiscent of the Thouless energy…

We perform neutrino radiation-hydrodynamics simulations for the merger of asymmetric binary neutron stars in numerical relativity. Neutron stars are modeled by soft and moderately stiff finite-temperature equations of state (EOS). We find that the properties of the dynamical ejecta such as the total mass, neutron richness profile, and specific entropy profile depend on the mass ratio of the binary systems for a given EOS in a unique manner. For a soft EOS (SFHo), the total ejecta mass depends weakly on the mass ratio, but the average of electron number per baryon (${Y}_{e}$) and specific entropy ($s$) of the ejecta decreases significantly with the increase of the degree of mass asymmetry. For a stiff EOS (DD2), with the increase of the mass asymmetry degree, the total ejecta mass significantly increases while the average of ${Y}_{e}$ and $s$ moderately decreases. We find again that only for the SFHo, the total ejecta mass exceeds $0.01{M}_{\ensuremath{\bigodot}}$ irrespective of the mass ratio chosen in this paper. The ejecta have a variety of electron number per baryon with an…

Using three-dimensional simulations, we study the dynamics and final structure of merging solitonic cores predicted to form in ultralight axion dark matter halos. The classical, Newtonian equations of motion of a self-gravitating scalar field are described by the Schr\"odinger-Poisson equations. We investigate mergers of ground state (boson star) configurations with varying mass ratios, relative phases, orbital angular momenta and initial separation with the primary goal to understand the mass loss of the emerging core by gravitational cooling. Previous results showing that the final density profiles have solitonic cores and Navarro-Frenk-White-like tails are confirmed. In binary mergers, the final core mass does not depend on initial phase difference or angular momentum and only depends on mass ratio, total initial mass, and total energy of the system. For nonzero angular momenta, the otherwise spherical cores become rotating ellipsoids. The results for mergers of multiple cores are qualitatively identical.

We present a new set of leading-twist parton distribution functions, referred to as ``CJ15,'' which take advantage of developments in the theoretical treatment of nuclear corrections as well as new data. The analysis includes, for the first time, data on the free neutron structure function from Jefferson Lab and new high-precision charged lepton and $W$-boson asymmetry data from Fermilab. These significantly reduce the uncertainty on the $d/u$ ratio at large values of $x$ and provide new insights into the partonic structure of bound nucleons.

After important upgrades to the experiment, the Super-Kamiokande collaboration returns to measuring the solar mixing angle and the mass splitting $\mathrm{\ensuremath{\Delta}}\phantom{\rule{0}{0ex}}{m}_{12}^{2}$. By focusing on low-energy ${}^{8}B$ neutrinos, the collaboration is able to single out neutrinos that undergo flavor conversion only through vacuum oscillations. The results are the currently most precise values for the mixing and mass-difference parameters relevant for vacuum solar neutrino oscillations.

We present a renormalizable theory of scalars in which the low-energy effective theory contains a pseudo-Goldstone boson with a compact field space of $2\ensuremath{\pi}F$ and an approximate discrete shift symmetry ${\mathcal{Z}}_{Q}$ with $Q\ensuremath{\gg}1$, yet the number of fields in the theory goes as $\mathrm{log}Q$. Such a model can serve as a UV completion to models of relaxions and is a new source of exponential scale separation in field theory. While the model is local in ``theory space,'' it appears not to have a continuum generalization (i.e., it cannot be a deconstructed extra dimension). Our framework shows that super-Planckian field excursions can be mimicked while sticking to renormalizable four-dimensional quantum field theory. We show that a supersymmetric extension is straightforwardly obtained, and we illustrate possible UV completions based on a compact extra dimension, where all global symmetries arise accidentally as a consequence of gauge invariance and five-dimensional locality.

We discuss the mass-radius diagram for static neutron star models obtained by the numerical solution of modified Tolman-Oppenheimer-Volkoff equations in $f(R)$ gravity where the Lagrangians $f(R)=R+\ensuremath{\alpha}{R}^{2}(1+\ensuremath{\gamma}R)$ and $f(R)={R}^{1+\ensuremath{\epsilon}}$ are adopted. Unlike the case of the perturbative approach previously reported, the solutions are constrained by the presence of an extra degree of freedom, coming from the trace of the field equations. In particular, the stiffness of the equation of state determines an upper limit on the central density ${\ensuremath{\rho}}_{\mathrm{c}}$ above which the positivity condition of energy-matter tensor trace ${T}^{\mathrm{m}}=\ensuremath{\rho}\ensuremath{-}3p$ holds. In the case of quadratic $f(R)$ gravity, we find higher masses and radii at lower central densities with an inversion of the behavior around a pivoting ${\ensuremath{\rho}}_{c}$ which depends on the choice of the equation of state. When considering the cubic corrections, we find solutions converging to the required asymptotic behavior of…

We discuss a possible extension of calculations of the bending angle of light in a static, spherically symmetric and asymptotically flat spacetime to a nonasymptotically flat case. We examine a relation between the bending angle of light and the Gauss-Bonnet theorem by using the optical metric. A correspondence between the deflection angle of light and the surface integral of the Gaussian curvature may allow us to take account of the finite distance from a lens object to a light source and a receiver. Using this relation, we propose a method for calculating the bending angle of light for such cases. Finally, this method is applied to two examples of the nonasymptotically flat spacetimes to suggest finite-distance corrections: the Kottler (Schwarzschild--de Sitter) solution to the Einstein equation and an exact solution in Weyl conformal gravity.

Tidal effects have an important impact on the late inspiral of compact binary systems containing neutron stars. Most current models of tidal deformations of neutron stars assume that the tidal bulge is directly related to the tidal field generated by the companion, with a constant response coefficient. However, if the orbital motion approaches a resonance with one of the internal modes of the neutron star, this adiabatic description of tidal effects starts to break down, and the tides become dynamical. In this paper, we consider dynamical tides in general relativity due to the quadrupolar fundamental oscillation mode of a neutron star. We devise a description of the effects of the neutron star's finite size on the orbital dynamics based on an effective point-particle action augmented by dynamical quadrupolar degrees of freedom. We analyze the post-Newtonian and test-particle approximations of this model and incorporate the results into an effective-one-body Hamiltonian. This enables us to extend the description of dynamical tides over the entire inspiral. We demonstrate that…

Following previous work of ours in spherical symmetry, we here propose a new parametric framework to describe the spacetime of axisymmetric black holes in generic metric theories of gravity. In this case, the metric components are functions of both the radial and the polar angular coordinates, forcing a double expansion to obtain a generic axisymmetric metric expression. In particular, we use a continued-fraction expansion in terms of a compactified radial coordinate to express the radial dependence, while we exploit a Taylor expansion in terms of the cosine of the polar angle for the polar dependence. These choices lead to a superior convergence in the radial direction and to an exact limit on the equatorial plane. As a validation of our approach, we build parametrized representations of Kerr, rotating dilaton, and Einstein-dilaton-Gauss-Bonnet black holes. The match is already very good at lowest order in the expansion and improves as new orders are added. We expect a similar behavior for any stationary and axisymmetric black-hole metric.

The mass of the dark matter particle is unknown, and may be as low as $\ensuremath{\sim}1{0}^{\ensuremath{-}22}\text{ }\text{ }\mathrm{eV}$. The lighter part of this range, below $\ensuremath{\sim}\mathrm{eV}$, is relatively unexplored both theoretically and experimentally but contains an array of natural dark matter candidates. An example is the relaxion, a light boson predicted by cosmological solutions to the hierarchy problem. One of the few generic signals such light dark matter can produce is a time-oscillating, equivalence-principle-violating force. We propose searches for this using accelerometers, and consider in detail the examples of torsion balances, atom interferometry, and pulsar timing. These approaches have the potential to probe large parts of unexplored parameter space in the next several years. Thus such accelerometers provide radically new avenues for the direct detection of dark matter.

We systematically study light ($<\text{few}\text{ }\mathrm{GeV}$) dark matter (DM) models that thermalize with visible matter through the Higgs portal and identify the remaining gaps in the viable parameter space. Such models require a comparably light scalar mediator that mixes with the Higgs to avoid DM overproduction and can be classified according to whether this mediator decays (in)visibly. In a representative benchmark model with Dirac fermion DM, we find that, even with conservative assumptions about the DM-mediator coupling and mass ratio, the regime in which the mediator is heavier than the DM is fully ruled out by a combination of collider, rare meson decay, and direct detection limits; future and planned experiments including NA62 can further improve sensitivity to scenarios in which the Higgs portal interaction does not determine the DM abundance. The opposite regime in which the mediator is lighter than the DM and the latter annihilates to pairs of visibly decaying mediators is still viable, but much of the parameter space is covered by rare meson decay, supernova…

We investigate Landau gauge $SU(3)$ Yang-Mills theory in a systematic vertex expansion scheme for the effective action with the functional renormalization group. Particular focus is put on the dynamical creation of the gluon mass gap at nonperturbative momenta and the consistent treatment of quadratic divergences. The nonperturbative ghost and transverse gluon propagators as well as the momentum-dependent ghost-gluon, three-gluon and four-gluon vertices are calculated self-consistently with the classical action as the only input. The apparent convergence of the expansion scheme is discussed and within the errors, our numerical results are in quantitative agreement with available lattice results.

We reexamine the determination of $|{V}_{cb}|$ from $B\ensuremath{\rightarrow}Dl\ensuremath{\nu}$ in view of recent experimental and theoretical progress, discussing the parameterization of the form factors and studying the role played by the unitarity constraints. Our fit to experimental and lattice results for $B\ensuremath{\rightarrow}D\ensuremath{\ell}\ensuremath{\nu}$ gives $|{V}_{cb}|=40.49(97){10}^{\ensuremath{-}3}$ and to $R(D)=0.299(3)$.

We formulate an effective theory of structure formation (ETHOS) that enables cosmological structure formation to be computed in almost any microphysical model of dark matter physics. This framework maps the detailed microphysical theories of particle dark matter interactions into the physical effective parameters that shape the linear matter power spectrum and the self-interaction transfer cross section of nonrelativistic dark matter. These are the input to structure formation simulations, which follow the evolution of the cosmological and galactic dark matter distributions. Models with similar effective parameters in ETHOS but with different dark particle physics would nevertheless result in similar dark matter distributions. We present a general method to map an ultraviolet complete or effective field theory of low-energy dark matter physics into parameters that affect the linear matter power spectrum and carry out this mapping for several representative particle models. We further propose a simple but useful choice for characterizing the dark matter self-interaction transfer…

At the extreme energies of the Large Hadron Collider, massive particles can be produced at such high velocities that their hadronic decays are collimated and the resulting jets overlap. Deducing whether the substructure of an observed jet is due to a low-mass single particle or due to multiple decay objects of a massive particle is an important problem in the analysis of collider data. Traditional approaches have relied on expert features designed to detect energy deposition patterns in the calorimeter, but the complexity of the data make this task an excellent candidate for the application of machine learning tools. The data collected by the detector can be treated as a two-dimensional image, lending itself to the natural application of image classification techniques. In this work, we apply deep neural networks with a mixture of locally connected and fully connected nodes. Our experiments demonstrate that without the aid of expert features, such networks match or modestly outperform the current state-of-the-art approach for discriminating between jets from single hadronic…

Any injection of electromagnetically interacting particles during the cosmic dark ages will lead to increased ionization, heating, production of Lyman-$\ensuremath{\alpha}$ photons and distortions to the energy spectrum of the cosmic microwave background, with potentially observable consequences. In this paper we describe numerical results for the low-energy electrons and photons produced by the cooling of particles injected at energies from keV to multi-TeV scales, at arbitrary injection redshifts (but focusing on the post-recombination epoch). We use these data, combined with existing calculations modeling the cooling of these low-energy particles, to estimate the resulting contributions to ionization, excitation and heating of the gas, and production of low-energy photons below the threshold for excitation and ionization. We compute corrected deposition-efficiency curves for annihilating dark matter, and demonstrate how to compute equivalent curves for arbitrary energy-injection histories. These calculations provide the necessary inputs for the limits on dark matter annihilation…

Gravitational waves emitted by distorted black holes---such as those arising from the coalescence of two neutron stars or black holes---carry not only information about the corresponding spacetime but also about the underlying theory of gravity. Although general relativity remains the simplest, most elegant, and viable theory of gravitation, there are generic and robust arguments indicating that it is not the ultimate description of the gravitational universe. Here, we focus on a particularly appealing extension of general relativity, which corrects Einstein's theory through the addition of terms which are second order in curvature: the topological Gauss-Bonnet invariant coupled to a dilaton. We study gravitational-wave emission from black holes in this theory and (i) find strong evidence that black holes are linearly (mode) stable against both axial and polar perturbations, (ii) discuss how the quasinormal modes of black holes can be excited during collisions involving black holes, and finally (iii) show that future ringdown detections with a large signal-to-noise ratio would…

We study the transverse-momentum-dependent (TMD) evolution of the Collins azimuthal asymmetries in ${e}^{+}{e}^{\ensuremath{-}}$ annihilations and semi-inclusive hadron production in deep inelastic scattering processes. All the relevant coefficients are calculated up to the next-to-leading-logarithmic-order accuracy. By applying the TMD evolution at the approximate next-to-leading-logarithmic order in the Collins-Soper-Sterman formalism, we extract transversity distributions for $u$ and $d$ quarks and Collins fragmentation functions from current experimental data by a global analysis of the Collins asymmetries in back-to-back dihadron productions in ${e}^{+}{e}^{\ensuremath{-}}$ annihilations measured by BELLE and BABAR collaborations and semi-inclusive hadron production in deep inelastic scattering data from HERMES, COMPASS, and JLab HALL A experiments. The impact of the evolution effects and the relevant theoretical uncertainties are discussed. We further discuss the TMD interpretation for our results and illustrate the unpolarized quark distribution, transversity distribution,…

We consider limits on the local ($z=0$) density (${n}_{0}$) of extragalactic neutrino sources set by the nondetection of steady high-energy neutrino sources producing $\ensuremath{\gtrsim}50\text{ }\text{ }\mathrm{TeV}$ muon multiplets in the present IceCube data, taking into account the redshift evolution, luminosity function, and neutrino spectrum of the sources. We show that the lower limit depends moderately on source spectra and strongly on redshift evolution. We find ${n}_{0}\ensuremath{\gtrsim}{10}^{\ensuremath{-}8}--{10}^{\ensuremath{-}7}\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}3}$ for standard candle sources evolving rapidly, ${n}_{s}\ensuremath{\propto}{(1+z)}^{3}$, and ${n}_{0}\ensuremath{\gtrsim}{10}^{\ensuremath{-}6}--{10}^{\ensuremath{-}5}\text{ }\text{ }{\mathrm{Mpc}}^{\ensuremath{-}3}$ for nonevolving sources. The corresponding upper limits on their neutrino luminosity are ${L}_{{\ensuremath{\nu}}_{\ensuremath{\mu}}}^{\mathrm{eff}}\ensuremath{\lesssim}1{0}^{42}--1{0}^{43}\text{ }\text{ }\mathrm{erg}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ and…

We show that a model with a scalar leptoquark of hypercharge $Y=1/6$ which includes light right-handed neutrinos can successfully describe both of the $B$-physics anomalies, ${R}_{K}^{\mathrm{exp}}<{R}_{K}^{\mathrm{SM}}$ and ${R}_{D}^{\mathrm{exp}}>{R}_{D}^{\mathrm{SM}}$. We discuss the corresponding low energy effective theory and, after using the known experimental data as constraints, we show that the model is viable and that it offers several predictions which can be tested experimentally.

The asymptotic safety conjecture is examined for quantum gravity in four dimensions. Using the renormalization group, we find evidence for an interacting UV fixed point for polynomial actions up to the 34th power in the Ricci scalar. The extrapolation to infinite polynomial order is given, and the self-consistency of the fixed point is established using a bootstrap test. All details of our analysis are provided. We also clarify further aspects such as stability, convergence, the role of boundary conditions, and a partial degeneracy of eigenvalues. Within this setting we find strong support for the conjecture.

We investigate irregularity factors for a self-gravitating spherical star evolving in the presence of an imperfect fluid. We explore the gravitational field equations and the dynamical equations with the systematic construction in $f(R,T)$ gravity, where $T$ is the trace of the energy-momentum tensor. Furthermore, we analyze two well-known differential equations (which occupy principal importance in the exploration of causes of energy density inhomogeneities) with the help of the Weyl tensor and the conservation laws. The irregularity factors for a spherical star are examined for particular cases of dust and isotropic and anisotropic fluids in dissipative and nondissipative regimes in the framework of $f(R,T)$ gravity. It is found that, as the complexity of the matter with the anisotropic stresses increases, the inhomogeneity factor corresponds more closely to one of the structure scalars.

With the physical Higgs mass the standard model symmetry restoration phase transition is a smooth cross-over. We study the thermodynamics of the cross-over using numerical lattice Monte Carlo simulations of an effective $\mathrm{SU}(2)\ifmmode\times\else\texttimes\fi{}\mathrm{U}(1)$ $\text{gauge}+\text{Higgs}$ theory, significantly improving on previously published results. We measure the Higgs field expectation value, thermodynamic quantities like pressure, energy density, speed of sound and heat capacity, and screening masses associated with the Higgs and $Z$ fields. While the cross-over is smooth, it is very well defined with a width of only $\ensuremath{\sim}5\text{ }\text{ }\mathrm{GeV}$. We measure the cross-over temperature from the maximum of the susceptibility of the Higgs condensate, with the result ${T}_{c}=159.5\ifmmode\pm\else\textpm\fi{}1.5\text{ }\text{ }\mathrm{GeV}$. Outside of the narrow cross-over region the perturbative results agree well with nonperturbative ones.

We consider the possibility of an interaction in the dark sector in the presence of massive neutrinos and study the observational constraints on three different scenarios of massive neutrinos using the most recent cosmic microwave background anisotropy data in combination with type Ia supernovae, baryon acoustic oscillations, and Hubble parameter measurements. When a sterile neutrino is introduced into the interacting dark sector scenario in addition to the standard model prediction of neutrinos, we find that the coupling parameter is nonzero at a $2\ensuremath{\sigma}$ confidence level. The interaction model with a sterile neutrino is also found to be a promising one to alleviate the current tension on the Hubble constant. We do not find the evidence for a coupling in the dark sector when the possibility of a sterile neutrino is discarded.

A number of works have shown that important information on the equation of state of matter at nuclear density can be extracted from the gravitational waves emitted by merging neutron-star binaries. We present a comprehensive analysis of the gravitational-wave signal emitted during the inspiral, merger, and postmerger of 56 neutron-star binaries. This sample of binaries, arguably the largest studied to date with realistic equations of state, spans six different nuclear-physics equations of state and ten masses, allowing us to sharpen a number of results recently obtained on the spectral properties of the gravitational-wave signal. Overall we find the following: (i) for binaries with masses differing no more than 20%, the frequency at gravitational-wave amplitude's maximum is related quasiuniversally with the tidal deformability of the two stars; (ii) the spectral properties vary during the postmerger phase, with a transient phase lasting a few milliseconds after the merger and followed by a quasistationary phase; (iii) when distinguishing the spectral peaks between these two phases,…

We prove the quantum null energy condition (QNEC), a lower bound on the stress tensor in terms of the second variation in a null direction of the entropy of a region. The QNEC arose previously as a consequence of the quantum focusing conjecture, a proposal about quantum gravity. The QNEC itself does not involve gravity, so a proof within quantum field theory is possible. Our proof is somewhat nontrivial, suggesting that there may be alternative formulations of quantum field theory that make the QNEC more manifest. Our proof applies to free and super-renormalizable bosonic field theories, and to any points that lie on stationary null surfaces. An example is Minkowski space, where any point $p$ and null vector ${k}^{a}$ define a null plane $N$ (a Rindler horizon). Given any codimension-2 surface $\mathrm{\ensuremath{\Sigma}}$ that contains $p$ and lies on $N$, one can consider the von Neumann entropy ${S}_{\mathrm{out}}$ of the quantum state restricted to one side of $\mathrm{\ensuremath{\Sigma}}$. A second variation ${S}_{\mathrm{out}}^{\ensuremath{'}\ensuremath{'}}$ can be defined…

We study a coupled quintessence model with pure momentum exchange and present the effects of such an interaction on the cosmic microwave background (CMB) and matter power spectrum. For a wide range of negative values of the coupling parameter $\ensuremath{\beta}$ structure growth is suppressed and the model can reconcile the tension between cosmic microwave background observations and structure growth inferred from cluster counts. We find that this model is as good as $\mathrm{\ensuremath{\Lambda}}\mathrm{CDM}$ for CMB and baryon acoustic oscillation data, while the addition of cluster data makes the model strongly preferred, improving the best-fit ${\ensuremath{\chi}}^{2}$ value by more than 16.

The mere existence of six-dimensional supersymmetric ``$(2,0)$'' conformal field theories implies many deep, nonperturbative dualities within the landscape of four- and three- dimensional quantum field theories. All evidence for these $6D$ theories is indirect and they are intrinsically nonperturbative, defying a conventional (Lagrangian) definition. This paper pushes methods developed for two dimensions (``bootstrap'') to higher dimensions, exploiting symmetries and numerical methods to obtain, for the first time, concrete results for the spectrum, correlation functions, etc., of these mysterious theories, without resorting to simplifying limitations.

Neutron star mergers are among the most promising sources of gravitational waves for advanced ground-based detectors. These mergers are also expected to power bright electromagnetic signals, in the form of short gamma-ray bursts, infrared/optical transients powered by r-process nucleosynthesis in neutron-rich material ejected by the merger, and radio emission from the interaction of that ejecta with the interstellar medium. Simulations of these mergers with fully general relativistic codes are critical to understand the merger and postmerger gravitational wave signals and their neutrinos and electromagnetic counterparts. In this paper, we employ the Spectral Einstein Code to simulate the merger of low mass neutron star binaries (two $1.2{M}_{\ensuremath{\bigodot}}$ neutron stars) for a set of three nuclear-theory-based, finite temperature equations of state. We show that the frequency peaks of the postmerger gravitational wave signal are in good agreement with predictions obtained from recent simulations using a simpler treatment of gravity. We find, however, that only the…

Hadrons in lattice QCD are usually created employing smeared interpolators. We introduce a new quark smearing that allows us to maintain small statistical errors and good overlaps of hadronic wave functions with the respective ground states, also at high spatial momenta. The method is successfully tested for the pion and the nucleon at a pion mass ${m}_{\ensuremath{\pi}}\ensuremath{\approx}295\text{ }\text{ }\mathrm{MeV}$ and momenta as high as 2.8 GeV. We compare the results obtained to dispersion relations and suggest further optimizations.

Loop amplitudes are conveniently expressed in terms of master integrals whose coefficients carry the process dependent information. Similarly before integration, the loop integrands may be expressed as a linear combination of propagator products with universal numerator tensors. Such a decomposition is an important input for the numerical unitarity approach, which constructs integrand coefficients from on-shell tree amplitudes. We present a new method to organize multiloop integrands into a direct sum of terms that integrate to zero (surface terms) and remaining master integrands. This decomposition facilitates a general, numerical unitarity approach for multiloop amplitudes circumventing analytic integral reduction. Vanishing integrals are well known as integration-by-parts identities. Our construction can be viewed as an explicit construction of a complete set of integration-by-parts identities excluding doubled propagators. Interestingly, a class of ``horizontal'' identities is singled out which hold as well for altered propagator powers.

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of $3.2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ at $\sqrt{s}=13\text{ }\text{ }\mathrm{TeV}$ collected in 2015 with the ATLAS detector at the Large Hadron Collider. Events are required to have at least one jet with a transverse momentum above 250 GeV and no leptons. Several signal regions are considered with increasing missing-transverse-momentum requirements between ${E}_{\mathrm{T}}^{\mathrm{miss}}>250\text{ }\text{ }\mathrm{GeV}$ and ${E}_{\mathrm{T}}^{\mathrm{miss}}>700\text{ }\text{ }\mathrm{GeV}$. Good agreement is observed between the number of events in data and Standard Model predictions. The results are translated into exclusion limits in models with large extra spatial dimensions, pair production of weakly interacting dark-matter candidates, and the production of supersymmetric particles in several compressed scenarios.

In the cosmological scenario in $f(T)$ gravity, we find analytical solutions for an isotropic and homogeneous universe containing a dust fluid and radiation and for an empty anisotropic Bianchi I universe. The method that we apply is that of movable singularities of differential equations. For the isotropic universe, the solutions are expressed in terms of a Laurent expansion, while for the anisotropic universe we find a family of exact Kasner-like solutions in vacuum. Finally, we discuss when a nonlinear $f(T)$-gravity theory provides solutions for the teleparallel equivalence of general relativity and derive conditions for exact solutions of general relativity to solve the field equations of an $f(T)$ theory.

We drastically simplify the problem of linearizing a general higher-order theory of gravity. We reduce it to the evaluation of its Lagrangian on a particular Riemann tensor depending on two parameters, and the computation of two derivatives with respect to one of those parameters. We use our method to construct a $D$-dimensional cubic theory of gravity which satisfies the following properties: (1) it shares the spectrum of Einstein gravity, i.e., it only propagates a transverse and massless graviton on a maximally symmetric background; (2) it is defined in the same way in general dimensions; (3) it is neither trivial nor topological in four dimensions. Up to cubic order in curvature, the only previously known theories satisfying the first two requirements are the Lovelock ones. We show that, up to cubic order, there exists only one additional theory satisfying requirements (1) and (2). Interestingly, this theory is, along with Einstein gravity, the only one which also satisfies (3).

We show that the integration-by-parts reductions of various two-loop integral topologies can be efficiently obtained by applying unitarity cuts to a specific set of subgraphs and solving associated polynomial (syzygy) equations.

Observations of gravitational lenses in strong gravitational fields give us a clue to understanding dark compact objects. In this paper, we extend a method to obtain a deflection angle in a strong deflection limit provided by Bozza [Phys. Rev. D 66, 103001 (2002)] to apply to ultrastatic spacetimes. We also discuss on the order of an error term in the deflection angle. Using the improved method, we consider gravitational lensing by an Ellis wormhole, which is an ultrastatic wormhole of the Morris-Thorne class.

The recent announcement by LIGO of the detection of the gravitational-wave signal GW150914 has ignited tremendous interest. The two manuscripts highlighted here detail the impressive analysis performed by LIGO to identify a specific black hole binary merger as the source of GW150914. The papers describe two independent methods of analysis: the matching of the signal to numerical-relativity-generated templates and unmodeled burst analyses. The two papers together provide detailed and virtually incontrovertible evidence, by the standards of experimental physics, of the detection of gravitational waves generated by a merger of a black hole binary system consisting initially of black holes of approximately 36 and 29 solar masses.

Many models of physics beyond the standard model predict the existence of new Abelian forces with new gauge bosons mediating interactions between ``dark sectors'' and the standard model. We report a search for a dark boson ${Z}^{\ensuremath{'}}$ coupling only to the second and third generations of leptons in the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}{Z}^{\ensuremath{'}},{Z}^{\ensuremath{'}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ using $514\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected by the BABAR experiment. No significant signal is observed for ${Z}^{\ensuremath{'}}$ masses in the range 0.212--10 GeV. Limits on the coupling parameter ${g}^{\ensuremath{'}}$ as low as $7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ are derived, leading to improvements in the bounds compared to those previously derived from neutrino experiments.

Amplitudes derived from scattering data on elementary targets are basic inputs to neutrino-nucleus cross section predictions. A prominent example is the isovector axial nucleon form factor, ${F}_{A}({q}^{2})$, which controls charged current signal processes at accelerator-based neutrino oscillation experiments. Previous extractions of ${F}_{A}$ from neutrino-deuteron scattering data rely on a dipole shape assumption that introduces an unquantified error. A new analysis of world data for neutrino-deuteron scattering is performed using a model-independent, and systematically improvable, representation of ${F}_{A}$. A complete error budget for the nucleon isovector axial radius leads to ${r}_{A}^{2}=0.46(22)\text{ }\text{ }{\mathrm{fm}}^{2}$, with a much larger uncertainty than determined in the original analyses. The quasielastic neutrino-neutron cross section is determined as $\ensuremath{\sigma}({\ensuremath{\nu}}_{\ensuremath{\mu}}n\ensuremath{\rightarrow}{\ensuremath{\mu}}^{\ensuremath{-}}p){|}_{{E}_{\ensuremath{\nu}}=1\text{ }\text{…

The recent discovery of gravitational waves from mergers of $\ensuremath{\sim}10\text{ }\text{ }{M}_{\ensuremath{\bigodot}}$ black hole binaries has stimulated interested in primordial black hole (PBH) dark matter in this mass range. Microlensing and dynamical constraints exclude all of the dark matter in compact objects with a delta function mass function in the range ${10}^{\ensuremath{-}7}\ensuremath{\lesssim}M/{M}_{\ensuremath{\bigodot}}\ensuremath{\lesssim}1{0}^{5}$. However it has been argued that all of the dark matter could be composed of compact objects in this range with an extended mass function. We explicitly recalculate the microlensing and dynamical constraints for compact objects with an extended mass function which replicates the PBH mass function produced by inflation models. We find that the microlensing and dynamical constraints place conflicting constraints on the width of the mass function, and do not find a mass function which satisfies both constraints.

In a recent paper [P. V. P. Cunha, C. A. R. Herdeiro, E. Radu, and H. F. Runarsson, Phys. Rev. Lett. 115, 211102 (2015).], it was shown that the lensing of light around rotating boson stars and Kerr black holes with scalar hair can exhibit chaotic patterns. Since no separation of variables is known (or expected) for geodesic motion on these backgrounds, we examine the 2D effective potentials for photon trajectories, to obtain a deeper understanding of this phenomenon. We find that the emergence of stable light rings on the background spacetimes allows the formation of ``pockets'' in one of the effective potentials, for open sets of impact parameters, leading to an effective trapping of some trajectories, dubbed ``quasibound orbits.'' We conclude that pocket formation induces chaotic scattering, although not all chaotic orbits are associated to pockets. These and other features are illustrated in a gallery of examples, obtained with a new ray-tracing code, pyhole, which includes tools for a simple, simultaneous visualization of the effective potential, together with the spacetime…

We consider the $f(R,T)$ modified theory of gravity, in which the gravitational Lagrangian is given by an arbitrary function of the Ricci scalar and the trace of the energy-momentum tensor of the matter, in order to investigate the dark-matter effects on the galaxy scale. We obtain the metric components for a spherically symmetric and static spacetime in the vicinity of general relativity solutions. However, we concentrate on a specific model of the theory where the matter is minimally coupled to the geometry, and derive the metric components in the galactic halo. Then, we fix the components by the rotational velocities of the galaxies for the model, and show that the mass corresponding to the interaction term (which appears in the Einstein modified field equation) leads to a flat rotation curve in the halo of galaxies. In addition, for the proposed model, the light-deflection angle has been derived and drawn using some observed data.

We investigate the impact of unquenching effects on QCD Green's functions, in the form of quark-loop contributions to both the gluon propagator and three-gluon vertex, in a three-loop inspired truncation of the three-particle irreducible (3PI) effective action. The fully coupled system of Dyson-Schwinger equations for the quark-gluon, ghost-gluon and three-gluon vertices, together with the quark propagator, are solved self-consistently; our only input are the ghost and gluon propagators themselves that are constrained by calculations within lattice QCD. We find that the two different unquenching effects have roughly equal, but opposite, impact on the quark-gluon vertex and quark propagator, with an overall negative impact on the latter. By taking further derivatives of the 3PI effective action, we construct the corresponding quark-antiquark kernel of the Bethe-Salpeter equation for mesons. The leading component is gluon exchange between two fully dressed quark-gluon vertices, thus introducing for the first time an obvious scalar-scalar component to the binding. We gain access to…

We consider gamma-ray burst (GRB) jets that are choked by extended material as sources of high-energy cosmic neutrinos. We take into account the jet propagation physics both inside the progenitor star and the surrounding dense medium. Radiation constraints, which are relevant for high-energy neutrino production, are considered as well. Efficient shock acceleration of cosmic rays is possible for sufficiently low-power jets and/or jets buried in a dense, extended wind or outer envelope. Such conditions also favor GRB jets to become stalled, and the necessary conditions for stalling are explicitly derived. Such choked jets may explain transrelativistic supernovae (SNe) and low-luminosity (LL) GRBs, giving a unified picture of GRBs and GRB-SNe. Focusing on this unified scenario for GRBs, we calculate the resulting neutrino spectra from choked jets, including the relevant microphysical processes such as multipion production in $pp$ and $p\ensuremath{\gamma}$ interactions, as well as the energy losses of mesons and muons. We obtain diffuse neutrino spectra using the latest results for the…

We study the motion of charged particles in the field of a rotating black hole immersed into an external asymptotically uniform magnetic field, focusing on the epicyclic quasicircular orbits near the equatorial plane. Separating the circular orbits into four qualitatively different classes according to the sign of the canonical angular momentum of the motion and the orientation of the Lorentz force, we analyze the circular orbits using the so-called force formalism. We find the analytical solutions for the radial profiles of velocity, specific angular momentum, and specific energy of the circular orbits in dependence on the black-hole dimensionless spin and the magnetic field strength. The innermost stable circular orbits are determined for all four classes of the circular orbits. The stable circular orbits with an outward-oriented Lorentz force can extend to radii lower than the radius of the corresponding photon circular geodesic. We calculate the frequencies of the harmonic oscillatory motion of the charged particles in the radial and vertical directions related to the equatorial…

A new covariant generalization of Einstein's general relativity is developed which allows the existence of a term proportional to ${T}_{\ensuremath{\alpha}\ensuremath{\beta}}{T}^{\ensuremath{\alpha}\ensuremath{\beta}}$ in the action functional of the theory (${T}_{\ensuremath{\alpha}\ensuremath{\beta}}$ is the energy-momentum tensor). Consequently, the relevant field equations are different from general relativity only in the presence of matter sources. In the case of a charged black hole, we find exact solutions for the field equations. Applying this theory to a homogeneous and isotropic spacetime, we find that there is a maximum energy density ${\ensuremath{\rho}}_{\mathrm{max}}$, and correspondingly a minimum length ${a}_{\mathrm{min}}$, at the early Universe. This means that there is a bounce at early times, and this theory avoids the existence of an early-time singularity. Moreover, we show that this theory possesses a true sequence of cosmological eras. We also argue that, although in the context of the standard cosmological model the cosmological constant…

Liquid argon is a bright scintillator with potent particle identification properties, making it an attractive target for direct-detection dark matter searches. The DarkSide-50 dark matter search here reports the first WIMP search results obtained using a target of low-radioactivity argon. DarkSide-50 is a dark matter detector, using a two-phase liquid argon time projection chamber, located at the Laboratori Nazionali del Gran Sasso. The underground argon is shown to contain $^{39}\mathrm{Ar}$ at a level reduced by a factor $(1.4\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{3}$ relative to atmospheric argon. We report a background-free null result from $(2616\ifmmode\pm\else\textpm\fi{}43)\text{ }\text{ }\mathrm{kg}\text{ }\mathrm{d}$ of data, accumulated over 70.9 live days. When combined with our previous search using an atmospheric argon, the 90% C.L. upper limit on the WIMP-nucleon spin-independent cross section, based on zero events found in the WIMP search regions, is $2.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}44}\text{ }\text{…

We present an analysis of the dynamics of two-flavor QCD in the vacuum. Special attention is paid to the transition from the high-energy quark-gluon regime to the low-energy regime governed by hadron dynamics. This is done within a functional renormalization group approach to QCD amended by dynamical hadronization techniques. These techniques allow us to describe conveniently the transition from the perturbative high-energy regime to the nonperturbative low-energy limit without suffering from a fine-tuning of model parameters. In the present work, we apply these techniques to two-flavor QCD with physical quark masses and show how the dynamics of the dominant low-energy degrees of freedom emerge from the underlying quark-gluon dynamics.

We calculate---for the first time in three-flavor lattice QCD---the hadronic matrix elements of all five local operators that contribute to neutral ${B}^{0}$- and ${B}_{s}$-meson mixing in and beyond the Standard Model. We present a complete error budget for each matrix element and also provide the full set of correlations among the matrix elements. We also present the corresponding bag parameters and their correlations, as well as specific combinations of the mixing matrix elements that enter the expression for the neutral $B$-meson width difference. We obtain the most precise determination to date of the SU(3)-breaking ratio $\ensuremath{\xi}=1.206(18)(6)$, where the second error stems from the omission of charm-sea quarks, while the first encompasses all other uncertainties. The threefold reduction in total uncertainty, relative to the 2013 Flavor Lattice Averaging Group results, tightens the constraint from $B$ mixing on the Cabibbo-Kobayashi-Maskawa (CKM) unitarity triangle. Our calculation employs gauge-field ensembles generated by the MILC Collaboration with four lattice…

We study the effect of a mass term in the spontaneous scalarization of neutron stars, for a wide range of scalar field parameters and neutron star equations of state. Even though massless scalars have been the focus of interest in spontaneous scalarization so far, recent observations of binary systems rule out most of their interesting parameter space. We point out that adding a mass term to the scalar field potential is a natural extension to the model that avoids these observational bounds if the Compton wavelength of the scalar is small compared to the binary separation. Our model is formally similar to the asymmetron scenario recently introduced in application to cosmology, though here we are interested in consequences for neutron stars and thus consider a mass term that does not modify the geometry on cosmological scales. We review the allowed values for the mass and scalarization parameters in the theory given current binary system observations and black hole spin measurements. We show that within the allowed ranges, spontaneous scalarization can have nonperturbative, strong…

Working in the framework of the Standard Model effective field theory, we study chirality-flipping couplings of the top quark to Higgs and gauge bosons. We discuss in detail the renormalization-group evolution to lower energies and investigate direct and indirect contributions to high- and low-energy $CP$-conserving and $CP$-violating observables. Our analysis includes constraints from collider observables, precision electroweak tests, flavor physics, and electric dipole moments. We find that indirect probes are competitive or dominant for both $CP$-even and $CP$-odd observables, even after accounting for uncertainties associated with hadronic and nuclear matrix elements, illustrating the importance of including operator mixing in constraining the Standard Model effective field theory. We also study scenarios where multiple anomalous top couplings are generated at the high scale, showing that while the bounds on individual couplings relax, strong correlations among couplings survive. Finally, we find that enforcing minimal flavor violation does not significantly affect the bounds on…

A new set of measurements of the top quark mass are presented, based on the proton-proton data recorded by the CMS experiment at the LHC at $\sqrt{s}=8\text{ }\text{ }\mathrm{TeV}$ corresponding to a luminosity of $19.7\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The top quark mass is measured using the $\text{lepton}+\text{jets}$, all-jets and dilepton decay channels, giving values of $172.35\ifmmode\pm\else\textpm\fi{}0.16(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.48(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}$, $172.32\ifmmode\pm\else\textpm\fi{}0.25(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.59(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}$, and $172.82\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0ex}{0ex}}0.19(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.22(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}$, respectively. When combined with the published CMS results at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$, they provide a top quark mass measurement of $172.44\ifmmode\pm\else\textpm\fi{}0.13(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.47(\mathrm{syst})\text{ }\text{ }\mathrm{GeV}$.…

I provide a frequency domain reduced order model (ROM) for the aligned-spin effective-one-body model ``SEOBNRv2'' for data analysis with second- and third-generation ground-based gravitational wave (GW) detectors. SEOBNRv2 models the dominant mode of the GWs emitted by the coalescence of black hole binaries. The large physical parameter space (dimensionless spins $\ensuremath{-}1\ensuremath{\le}{\ensuremath{\chi}}_{i}\ensuremath{\le}0.99$ and symmetric mass ratios $0.01\ensuremath{\le}\ensuremath{\eta}\ensuremath{\le}0.25$) requires sophisticated reduced order modeling techniques, including patching in the parameter space and in frequency. I find that the time window over which the inspiral-plunge and the merger-ringdown waveform in SEOBNRv2 are connected has a discontinuous dependence on the parameters when the spin parameter $\ensuremath{\chi}=0.8$ or the symmetric mass ratio $\ensuremath{\eta}\ensuremath{\sim}0.083$. This discontinuity increases resolution requirements for the ROM. The ROM can be used for compact binary systems with total masses of $2{M}_{\ensuremath{\bigodot}}$…

The most recent measurements of the temperature and low-multipole polarization anisotropies of the cosmic microwave background from the Planck satellite, when combined with galaxy clustering data from the Baryon Oscillation Spectroscopic Survey in the form of the full shape of the power spectrum, and with baryon acoustic oscillation measurements, provide a 95% confidence level (C.L.) upper bound on the sum of the three active neutrinos $\ensuremath{\sum}{m}_{\ensuremath{\nu}}<0.183\text{ }\text{ }\mathrm{eV}$, among the tightest neutrino mass bounds in the literature, to date, when the same data sets are taken into account. This very same data combination is able to set, at $\ensuremath{\sim}70%$ C.L., an upper limit on $\ensuremath{\sum}{m}_{\ensuremath{\nu}}$ of 0.0968 eV, a value that approximately corresponds to the minimal mass expected in the inverted neutrino mass hierarchy scenario. If high-multipole polarization data from Planck is also considered, the 95% C.L. upper bound is tightened to $\ensuremath{\sum}{m}_{\ensuremath{\nu}}<0.176\text{ }\text{ }\mathrm{eV}$. Further…

Inferring astrophysical information from gravitational waves emitted by compact binaries is one of the key science goals of gravitational-wave astronomy. In order to reach the full scientific potential of gravitational-wave experiments, we require techniques to mitigate the cost of Bayesian inference, especially as gravitational-wave signal models and analyses become increasingly sophisticated and detailed. Reduced-order models (ROMs) of gravitational waveforms can significantly reduce the computational cost of inference by removing redundant computations. In this paper, we construct the first reduced-order models of gravitational-wave signals that include the effects of spin precession, inspiral, merger, and ringdown in compact object binaries and that are valid for component masses describing binary neutron star, binary black hole, and mixed binary systems. This work utilizes the waveform model known as ``IMRPhenomPv2.'' Our ROM enables the use of a fast reduced-order quadrature (ROQ) integration rule which allows us to approximate Bayesian probability density functions at a…

Classification of jets as originating from light-flavor or heavy-flavor quarks is an important task for inferring the nature of particles produced in high-energy collisions. The large and variable dimensionality of the data provided by the tracking detectors makes this task difficult. The current state-of-the-art tools require expert data reduction to convert the data into a fixed low-dimensional form that can be effectively managed by shallow classifiers. We study the application of deep networks to this task, attempting classification at several levels of data, starting from a raw list of tracks. We find that the highest-level lowest-dimensionality expert information sacrifices information needed for classification, that the performance of current state-of-the-art taggers can be matched or slightly exceeded by deep-network-based taggers using only track and vertex information, that classification using only lowest-level highest-dimensionality tracking information remains a difficult task for deep networks, and that adding lower-level track and vertex information to the classifiers…

We calculate the properties of excited charm and charm-strange mesons. We use the relativized quark model to calculate their masses and wave functions that are used to calculate radiative transition partial widths and the ${^{3}P}_{0}$ quark-pair-creation model to calculate their strong decay widths. We use these results to make quark model spectroscopic assignments for recently observed charm and charm-strange mesons. In particular, we find that the properties of the ${D}_{J}(2550{)}^{0}$ and ${D}_{J}^{*}(2600{)}^{0}$ are consistent with those of the $2{^{1}S}_{0}(c\overline{u})$ and the $2{^{3}S}_{1}(c\overline{u})$ states respectively, and the ${D}_{1}^{*}(2760{)}^{0}$, ${D}_{3}^{*}(2760{)}^{\ensuremath{-}}$, and ${D}_{J}(2750{)}^{0}$ with those of the $1{^{3}D}_{1}(c\overline{u})$, $1{^{3}D}_{3}(d\overline{c})$, and $1{D}_{2}(c\overline{u})$ states respectively. We tentatively identify the ${D}_{J}^{*}(3000{)}^{0}$ as the $1{^{3}F}_{4}(c\overline{u})$ and favor the ${D}_{J}(3000{)}^{0}$ to be the $3{^{1}S}_{0}(c\overline{u})$ although we do not rule out the $1{F}_{3}$ and…

We present the first constraints on cosmology from the Dark Energy Survey (DES), using weak lensing measurements from the preliminary Science Verification (SV) data. We use 139 square degrees of SV data, which is less than 3% of the full DES survey area. Using cosmic shear 2-point measurements over three redshift bins we find ${\ensuremath{\sigma}}_{8}({\mathrm{\ensuremath{\Omega}}}_{\mathrm{m}}/0.3{)}^{0.5}=0.81\ifmmode\pm\else\textpm\fi{}0.06$ (68% confidence), after marginalizing over 7 systematics parameters and 3 other cosmological parameters. We examine the robustness of our results to the choice of data vector and systematics assumed, and find them to be stable. About 20% of our error bar comes from marginalizing over shear and photometric redshift calibration uncertainties. The current state-of-the-art cosmic shear measurements from CFHTLenS are mildly discrepant with the cosmological constraints from Planck CMB data; our results are consistent with both data sets. Our uncertainties are $\ensuremath{\sim}30%$ larger than those from CFHTLenS when we carry out a comparable…

Compact binary mergers involving at least one neutron star are important sources of gravitational waves. To fully describe such mergers, however, requires not only general relativity but also nuclear physics, hydrodynamics, and neutrino transport. The paper by Foucart et al. marks a significant step in this direction by showing the sensitivity of observables to the neutrino energy spectrum.

We study how two fully featured hydrogenlike atoms harvest entanglement from the electromagnetic field vacuum, even when the atoms are spacelike separated. We compare the electromagnetic case---qualitatively and quantitatively---with previous results that used scalar fields and featureless, idealized atomic models. Our study reveals the new traits that emerge when we relax these idealizations, such as anisotropies in entanglement harvesting and the effect of exchange of angular momentum. We show that, under certain circumstances, relaxing previous idealizations makes vacuum entanglement harvesting more efficient.

We present results of a dark matter search performed with a 0.6 kg d exposure of the DAMIC experiment at the SNOLAB underground laboratory. We measure the energy spectrum of ionization events in the bulk silicon of charge-coupled devices down to a signal of 60 eV electron equivalent. The data are consistent with radiogenic backgrounds, and constraints on the spin-independent WIMP-nucleon elastic-scattering cross section are accordingly placed. A region of parameter space relevant to the potential signal from the CDMS-II Si experiment is excluded using the same target for the first time. This result obtained with a limited exposure demonstrates the potential to explore the low-mass WIMP region ($<10\text{ }\text{ }\mathrm{GeV}\text{ }{c}^{\ensuremath{-}2}$) with the upcoming DAMIC100, a 100 g detector currently being installed in SNOLAB.

We critically examine the potential to disentangle the Standard Model (SM) and new physics (NP) in $B\ensuremath{\rightarrow}{K}^{*}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and $B\ensuremath{\rightarrow}{K}^{*}{e}^{+}{e}^{\ensuremath{-}}$ decays, focusing on (i) the LHCb anomaly, (ii) the search for right-handed currents, and (iii) lepton-universality violation. Restricting ourselves to the large-recoil region, we advocate a parametrization of the hadronic matrix elements that separates model-independent information about nonperturbative QCD from the results of model calculations. We clarify how to estimate corrections to the heavy-quark limit that would generate a right-handed (virtual) photon in the $b\ensuremath{\rightarrow}s\ensuremath{\gamma}$ contribution to the decay. We then apply this approach to the discussion of various sets of observables of increasing theoretical cleanness. First, we show that angular observables in the optimized ${P}_{i}^{(\ensuremath{'})}$ basis are, in general, still not robust against the long-distance QCD effects, both numerically…

We have analyzed the singularities of a triangle loop integral in detail and derived a formula for an easy evaluation of the triangle singularity on the physical boundary. It is applied to the ${\mathrm{\ensuremath{\Lambda}}}_{b}\ensuremath{\rightarrow}J/\ensuremath{\psi}{K}^{\ensuremath{-}}p$ process via ${\mathrm{\ensuremath{\Lambda}}}^{*}$-charmonium-proton intermediate states. Although the evaluation of absolute rates is not possible, we identify the ${\ensuremath{\chi}}_{c1}$ and the $\ensuremath{\psi}(2S)$ as the relatively most relevant states among all possible charmonia up to the $\ensuremath{\psi}(2S)$. The $\mathrm{\ensuremath{\Lambda}}(1890){\ensuremath{\chi}}_{c1}p$ loop is very special, as its normal threshold and triangle singularities merge at about 4.45 GeV, generating a narrow and prominent peak in the amplitude in the case that the ${\ensuremath{\chi}}_{c1}p$ is in an $S$ wave. We also see that loops with the same charmonium and other ${\mathrm{\ensuremath{\Lambda}}}^{*}$ hyperons produce less dramatic peaks from the threshold singularity alone. For the case of…

The excess recently reported by the ATLAS and CMS collaborations in the diphoton channel, if confirmed, is argued to require beyond standard model physics for an explanation. Four possible scenarios and some of their consequences are explored.

We present the CoLoRFulNNLO method to compute higher order radiative corrections to jet cross sections in perturbative QCD. We apply our method to the computation of event shape observables in electron-positron collisions at NNLO accuracy and validate our code by comparing our predictions to previous results in the literature. We also calculate for the first time jet cone energy fraction at NNLO.

We study the ultraviolet stability of gravity-matter systems for general numbers of minimally coupled scalars and fermions. This is done within the functional renormalization group setup put forward in [N. Christiansen, B. Knorr, J. Meibohm, J. M. Pawlowski, and M. Reichert, Phys. Rev. D 92, 121501 (2015).] for pure gravity. It includes full dynamical propagators and a genuine dynamical Newton's coupling, which is extracted from the graviton three-point function. We find ultraviolet stability of general gravity-fermion systems. Gravity-scalar systems are also found to be ultraviolet stable within validity bounds for the chosen generic class of regulators, based on the size of the anomalous dimension. Remarkably, the ultraviolet fixed points for the dynamical couplings are found to be significantly different from those of their associated background counterparts, once matter fields are included. In summary, the asymptotic safety scenario does not put constraints on the matter content of the theory within the validity bounds for the chosen generic class of regulators.

The fraction of the Universe going into primordial black holes (PBHs) with initial mass ${M}_{*}\ensuremath{\approx}5\ifmmode\times\else\texttimes\fi{}1{0}^{14}\text{ }\text{ }\mathrm{g}$, such that they are evaporating at the present epoch, is strongly constrained by observations of both the extragalactic and Galactic $\ensuremath{\gamma}$-ray backgrounds. However, while the dominant contribution to the extragalactic background comes from the time-integrated emission of PBHs with initial mass ${M}_{*}$, the Galactic background is dominated by the instantaneous emission of those with initial mass slightly larger than ${M}_{*}$ and current mass below ${M}_{*}$. Also, the instantaneous emission of PBHs smaller than $0.4{M}_{*}$ mostly comprises secondary particles produced by the decay of directly emitted quark and gluon jets. These points were missed in the earlier analysis by Lehoucq et al. using EGRET data. For a monochromatic PBH mass function, with initial mass $(1+\ensuremath{\mu}){M}_{*}$ and $\ensuremath{\mu}\ensuremath{\ll}1$, the current mass is…

Three-dimensional Einstein gravity with a negative cosmological constant admits stationary black holes that are not necessarily spherically symmetric. We propose boundary conditions for the near-horizon region of these black holes that lead to a surprisingly simple near-horizon symmetry algebra consisting of two affine $\stackrel{^}{u}(1)$ current algebras. The symmetry algebra is essentially equivalent to the Heisenberg algebra. The associated charges give a specific example of ``soft hair'' on the horizon, as defined by Hawking, Perry and Strominger. We show that soft hair does not contribute to the Bekenstein-Hawking entropy of Ba\~nados-Teitelboim-Zanelli black holes and ``black flower'' generalizations. From the near-horizon perspective the conformal generators at asymptotic infinity appear as composite operators, which we interpret in the spirit of black hole complementarity. Another remarkable feature of our boundary conditions is that they are singled out by requiring that the whole spectrum is compatible with regularity at the horizon, regardless of the value of the global…

We use the latest compilation of observational Hubble parameter measurements estimated with the differential evolution of cosmic chronometers, in combination with the local value of the Hubble constant recently measured with 2.4% precision, to constrain the cosmological scenario where dark energy interacts directly with the dark matter sector. To diminish the degeneracy between the parameters we additionally consider standard probes, such as supernovae type Ia from joint light-curve analysis samples, baryon acoustic oscillation distance measurements (BAO), and cosmic microwave background data from Planck 2015 estimations. Our analysis shows that the direct interaction between dark energy and dark matter is mildly favored, while the dark energy equation-of-state parameter is $w<\ensuremath{-}1$ at a $3\ensuremath{\sigma}$ confidence level.

Binary neutron star (NS) mergers are strong gravitational-wave (GW) sources and the leading candidates to interpret short-duration gamma-ray bursts (SGRBs). Under the assumptions that SGRBs are produced by double neutron star mergers and that the x-ray plateau followed by a steep decay as observed in SGRB x-ray light curves marks the collapse of a supramassive neutron star to a black hole (BH), we use the statistical observational properties of Swift SGRBs and the mass distribution of Galactic double neutron star systems to place constraints on the neutron star equation of state (EoS) and the properties of the post-merger product. We show that current observations already impose the following interesting constraints. (1) A neutron star EoS with a maximum mass close to a parametrization of ${M}_{\mathrm{max}}=2.37{M}_{\ensuremath{\bigodot}}(1+1.58\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}{P}^{\ensuremath{-}2.84})$ is favored. (2) The fractions for the several outcomes of NS-NS mergers are as follows: $\ensuremath{\sim}40%$ prompt BHs, $\ensuremath{\sim}30%$…