The 50 most-cited articles in Physical Review C, 2024

The multiplicity dependence of multistrange hadron yields in proton-proton and lead-lead collisions at several TeV allows one to study the transition from very big to very small systems, in particular, concerning collective effects. I investigate this, employing a core-corona approach based on new microcanonical hadronization procedures in the 4 framework, as well as new methods allowing one to transform energy-momentum flow through freeze-out surfaces into invariant-mass elements. I try to disentangle effects due to “canonical suppression” and “core-corona separation”, which will both lead to a reduction of the yields at low multiplicity. Published by the American Physical Society 2024

The exploration of nuclear mass or binding energy, a fundamental property of atomic nuclei, remains at the forefront of nuclear physics research due to limitations in experimental studies and uncertainties in model calculations, particularly when moving away from the stability line. In this work, we employ two machine learning (ML) models, support vector regression (SVR) and Gaussian process regression (GPR), to assess their performance in predicting nuclear mass excesses using available experimental data and a physics-based feature space. We also examine the extrapolation capabilities of these models using newly measured nuclei from AME2020 and by extending our calculations beyond the training and test set regions. Our results indicate that both SVR and GPR models perform quite well within the training and test regions when informed with a physics-based feature space. Furthermore, these ML models demonstrate the ability to make reasonable predictions away from the available experimental data, offering results comparable to the model calculations. Through further refinement, these…

I analyze the trajectory of the Lee-Yang edge singularities of the QCD equation of state in the complex baryon chemical potential ( μ B ) plane for different values of the temperature by using the recent lattice results for the Taylor expansion coefficients up to eighth order in μ B and various resummation techniques that blend in Padé expansions and conformal maps. By extrapolating from this information, I estimate for the location of the QCD critical point: T c ≈ 100 MeV, μ c ≈ 580 MeV. I also estimate the crossover slope at the critical point to be α 1 ≈ 9 ∘ and further constrain the nonuniversal mapping parameters between the three-dimensional Ising model and QCD equations of state. Published by the American Physical Society 2024

The recently published CREX results suggest a rather peculiar picture for the density dependence of the symmetry energy. Whereas PREX favors a large neutron skin thickness in $^{208}\mathrm{Pb}$, thereby suggesting a stiff equation of state, CREX suggests instead a much softer equation of state. This discrepancy has caused a large spur in the theoretical community, since no model has been able to simultaneously reproduce within $1\ensuremath{\sigma}$ the PREX and CREX results. Motivated by a novel correlation between a CREX observable and a combination of bulk symmetry energy parameters, we calibrate three new covariant energy density functionals that reproduce binding energies and charge radii of spherical nuclei---and also accommodate the constraints imposed by PREX and CREX. Given that these models suggest a stiff equation of state at high densities, predictions for neutron star properties are also discussed.

The interiors of neutron stars contain matter at the highest densities realized in our Universe. Interestingly, theoretical studies of dense matter, in combination with the existence of two-solar-mass neutron stars, indicate that the speed of sound ${c}_{s}$ has to increase to values well above the conformal limit (${c}_{s}^{2}=1/3$) before decreasing again at higher densities. The decrease could be explained by either a strong first-order phase transition or a crossover transition from hadronic to quark matter. The latter scenario leads to a pronounced peak in the speed of sound, reaching values above the conformal limit, naturally explaining the inferred behavior. In this work, we use the nuclear-physics multimessenger astrophysics (NMMA) framework to compare predictions of the quarkyonic matter model with astrophysical observations of neutron stars, with the goal of constraining model parameters. Assuming quarkyonic matter to be realized within neutron stars, we find that there can be a significant amount of quarks inside the cores of neutron stars with masses in the…

The $^{232}\mathrm{Th}$($^{48}\mathrm{Ca},5n$)$^{275}\mathrm{Ds}$ and $^{238}\mathrm{U}$($^{40}\mathrm{Ar},5n$)$^{273}\mathrm{Ds}$ reactions have been studied at the gas-filled separator DGFRS-2 at the Superheavy Element Factory at Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. For the first time, a new isotope $^{275}\mathrm{Ds}$ with a half-life of $0.{43}_{\ensuremath{-}0.12}^{+0.29}$ ms and \ensuremath{\alpha}-particle energy of $11.20\ifmmode\pm\else\textpm\fi{}0.02$ MeV was synthesized in the $^{48}\mathrm{Ca}$-induced reaction with the actinide nucleus and identified by measuring correlated \ensuremath{\alpha} decays ending in known nuclei. The decay properties of nuclei originating from $^{273}\mathrm{Ds}$ and $^{275}\mathrm{Ds}$ are compared with theoretical calculations and decay schemes are proposed. The cross sections of the $^{232}\mathrm{Th}$($^{48}\mathrm{Ca},5n$)$^{275}\mathrm{Ds}$ reaction of $0.{11}_{\ensuremath{-}0.09}^{+0.46}$ and $0.{34}_{\ensuremath{-}0.16}^{+0.59}$ pb were measured at excitation energies of the…

This paper compiles the model parameters and zero-temperature properties of an extensive collection of published theoretical nuclear interactions, including 255 nonrelativistic (Skyrme-like) forces, 270 relativistic mean field (RMF) and point-coupling (RMF-PC) forces, and 13 Gogny-like forces. This forms the most exhaustive tabulation of model parameters to date. The properties of uniform symmetric matter and pure neutron matter at the saturation density are determined. Symmetry properties found from the second-order term of a Taylor expansion in neutron excess are compared with the energy difference of pure neutron and symmetric nuclear matter at the saturation density. Selected liquid-droplet model parameters, including the surface tension and surface symmetry energy, are determined for semi-infinite surfaces. Theoretical liquid droplet model neutron skin thicknesses of the neutron-rich closed-shell nuclei $^{48}\mathrm{Ca}$ and $^{208}\mathrm{Pb}$ are compared with published theoretical Hartree-Fock and experimental results. A similar comparison is made between theoretical…

A linear Boltzmann transport (LBT) Monte Carlo model has been developed to describe jet propagation and interaction with the quark-gluon plasma (QGP) in relativistic heavy-ion collisions. A complete set of elastic-scattering processes and medium-induced gluon emissions based on the higher-twist formalism are incorporated for both jet shower and medium recoil partons. It has been employed to describe experimental data on large transverse momentum hadron and jet spectra, correlation and jet substructures in high-energy heavy-ion collisions. We document in detail the structure of the model and validation of the Monte Carlo implementations of the physics processes in LBT, in particular, the inelastic process of medium-induced gluon radiation. We carry out a comprehensive examination of the jet-medium interaction as implemented in LBT through energy loss and momentum broadening of a single hard parton, the energy and transverse momentum transfer from leading partons to medium-induced gluons and jet-induced medium excitation, and medium modification of reconstructed jets in a static and…

Within the framework of the dinuclear system model, the experimentally accessible projectile-target combinations are predicted for the production of new superheavy elements with $Z=119$ and $Z=120$. The entrance channel effect and the isotopic dependence of targets and projectiles on the capture, fusion, and survival stages of the fusion reaction are discussed. The reactions $^{45}\mathrm{Sc}+^{249}\mathrm{Cf}$ and $^{50}\mathrm{V} + ^{246}\mathrm{Cm}$ are found to be promising candidates for the synthesis of the element with $Z=119$, achieving the maximal evaporation residue cross sections of 0.288 pb at an incident energy of 211.2 MeV and 0.237 pb at an incident energy of 226.2 MeV, respectively. Meanwhile, the element with $Z=120$ can be synthesized through the reaction $^{46}\mathrm{Ti} + ^{249}\mathrm{Cf}$ with a maximal evaporation residue cross section of 0.040 pb at 221.8 MeV.

A new generation of phenomenological optical potentials requires robust calibration and uncertainty quantification, motivating the use of Bayesian statistical methods. These Bayesian methods usually require calculating observables for thousands or even millions of parameter sets, making fast and accurate emulators highly desirable or even essential. Emulating scattering across different energies or with interactions such as optical potentials is challenging because of the nonaffine parameter dependence, meaning the parameters do not all factorize from individual operators. Here we introduce and demonstrate the reduced-order scattering emulator (rose) framework, a reduced basis emulator that can handle nonaffine problems. rose is fully extensible and works within the publicly available band framework software suite for calibration, model mixing, and experimental design. As a demonstration problem, we use rose to calibrate a realistic nucleon-target scattering model through the calculation of elastic cross sections. This problem shows the practical value of the rose framework for…

Background: Nuclear masses are of fundamental importance in both nuclear physics and astrophysics, and the masses for most neutron-rich exotic nuclei are still beyond the experimental capability. The relativistic continuum Hartree-Bogoliubov (RCHB) theory has achieved great successes in the studies of both stable and exotic nuclei. The mass table based on the RCHB theory has been constructed with the assumption of spherical symmetry [Xia et al., At. Data Nucl. Data Tables 121, 1 (2018)]. The upgraded version including deformation effects based on the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) is under construction, and the part for even-even nuclei has been finished [Zhang et al., At. Data Nucl. Data Tables 144, 101488 (2022)]. The kernel ridge regression (KRR) approach is a useful machine-learning approach in refining nuclear mass prediction, and is found to be reliable in avoiding the risk of worsening predictions at large extrapolation distance [Wu and Zhao, Phys. Rev. C 101, 051301(R) (2020)].Purpose: The aim of this work is to combine the RCHB mass…

Ultrarelativistic heavy-ion collisions will first realize many nucleon-nucleon scatterings, happening instantaneously and therefore necessarily in parallel, due to the short collision time. An appropriate quantum mechanical tool to treat that problem is S-matrix theory, and it has been known for a long time how to derive a simple geometric probabilistic picture, still widely used, and here the Abramovskii-Gribov-Kancheli (AGK) theorem plays a crucial role. All this is done in a scenario where energy conservation is not taken care of, but this is needed, in particular for Monte Carlo simulations. When introducing energy-momentum sharing properly, the AGK theorem does not apply anymore, nor do simple geometric concepts such as binary scaling. I will discuss this (very serious) problem, and how it can be solved, in the EPOS4 framework. When connecting the multiple-Pomeron approach (for parallel scatterings) and perturbative QCD, one is actually forced to implement in a very particular way saturation scales in order to get an approach free of contradictions. One recovers a generalized…

The recent discovery of a central compact object (CCO) within the supernova remnant HESS J1731-347, characterized by a mass of approximately $0.{77}_{\ensuremath{-}0.17}^{+0.20} {M}_{\ensuremath{\bigodot}}$ and a radius of about $10.{4}_{\ensuremath{-}0.78}^{+0.86}$ km, has opened up a new window for the study of compact objects. This CCO is particularly intriguing because it is the lightest and smallest compact object ever observed, raising questions and challenging the existing theories. To account for this light compact star, a mean-field model within the framework of the parity doublet structure is applied to describe the hadron matter. Inside the model, part of the nucleon mass is associated with the chiral symmetry breaking while the other part is from the chiral invariant mass ${m}_{0}$ which is insensitive to the temperature and density. The value of ${m}_{0}$ affects the nuclear equation of state for uniform nuclear matter at low density and exhibits strong correlations with the radii of neutron stars. We point out that HESS J1731-347 can be explained as the lightest…

Heavy-flavor hadrons produced in ultrarelativistic heavy-ion collisions are a sensitive probe for studying hadronization mechanisms of the quark-gluon-plasma. In this paper, we survey how different transport models for the simulation of heavy-quark diffusion through a quark-gluon plasma in heavy-ion collisions implement hadronization and how this affects final state observables. Utilizing the same input charm-quark distribution in all models at the hadronization transition, we find that the transverse-momentum dependence of the nuclear modification factor of various charm hadron species has significant sensitivity to the hadronization scheme. In addition, the charm-hadron elliptic flow exhibits a nontrivial dependence on the elliptic flow of the hadronizing partonic medium. Published by the American Physical Society 2024

The authors propose a new approach for the calculation of nuclear-dependent corrections to superallowed $\ensuremath{\beta}$ decays based on effective field theory (EFT). The calculation is timely given the observation in recent years of a 2--3 $\ensuremath{\sigma}$ anomaly in the test of the first row of the Cabibbo-Kobayashi-Maskawa matrix. Within a comprehensive assessment, the authors methodically develop a master formula for superallowed $\ensuremath{\beta}$ decays, paving the way for $a\phantom{\rule{0}{0ex}}b$-$i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ nuclear many-body computations of nuclear-structure-dependent corrections. The results show promise for state-of-the-art extractions of ${V}_{u\phantom{\rule{0}{0ex}}d}$ from nuclear processes with controlled uncertainty quantification, and for using precision $\ensuremath{\beta}$-decay experiments to search for physics beyond the standard model.

The authors perform rigorous Bayesian inference on a variety of measurements in relativistic Pb-Pb collisions at the LHC using a comprehensive multistage model combining QCD-based initial states with viscous hydrodynamics and a hadronic afterburner. In particular, they extracted systematic constraints on the temperature dependence of shear and bulk viscosities of quark-gluon plasma that are significantly more precise due to improved physical models and statistical methods. For the range of plasma temperature probed in heavy-ion collisions, they find that the specific bulk viscosity demanded by the data is strongly non-zero and temperature-dependent, whereas the specific shear viscosity shows a much weaker temperature dependence that is indistinguishable from a constant value even with improved statistical analysis. Importantly, the authors showcase the application of transfer learning to efficiently explore a range of model uncertainties wider than had been considered previously. This work represents a substantial advancement in constraining the shear and bulk viscosities of…

Probing the $\ensuremath{\alpha}$ cluster of $^{16}\mathrm{O}$ with the relativistic $^{16}\mathrm{O}+^{16}\mathrm{O}$ collisions has raised great interest in the heavy ion community. However, the effects of the $\ensuremath{\alpha}$ cluster on the soft hadron observables vary largely among different studies. In this paper, we explain the differences by the compactness of the $\ensuremath{\alpha}$ cluster in oxygen, using iEBE-VISHNU hydrodynamic simulations with different initial state $\ensuremath{\alpha}$ cluster configurations. We also find several observables, such as the intensive skewness of the $[{p}_{\mathrm{T}}]$ correlator ${\mathrm{\ensuremath{\Gamma}}}_{{p}_{\mathrm{T}}}$, the harmonic flows ${v}_{2}{2}, {v}_{2}{4}, {v}_{3}{2}$, and the ${v}_{n}^{2}\ensuremath{-}\ensuremath{\delta}[{p}_{\mathrm{T}}]$ correlations $\ensuremath{\rho}({v}_{2}^{2},[{p}_{\mathrm{T}}]), \ensuremath{\rho}({v}_{3}^{2},[{p}_{\mathrm{T}}])$ in $^{16}\mathrm{O}+^{16}\mathrm{O}$ collisions are sensitive to the compactness of the $\ensuremath{\alpha}$ cluster in the colliding nuclei, which can be…

Properties of neutron stars such as their masses and radii arise from the characteristics of highly asymmetric nuclear matter (with many more neutrons than protons) which is not accessible in experiments. The authors consider a family of neutron-star equations of state characterized by a nontrivial behavior of nuclear matter at high densities, including a steep rise and then decline (i.e., a sharp peak) in the speed of sound with density, which is compatible with ultraheavy neutron stars up to 2.5 solar masses. The symmetry-energy expansion is then applied to obtain equations of state applicable to the almost symmetric nuclear matter created in heavy-ion collisions in the laboratory. The authors find that the description incorporating a sharp peak in the speed of sound profile aligns well with experimental data. The systematic approach opens promising perspectives for further investigations bridging the physics of neutron stars and heavy-ion collisions.

The measurement of the direct-photon spectrum from $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{{}_{NN}}}=200$ GeV is presented by the PHENIX Collaboration using the external-photon-conversion technique for 0%--93% central collisions in a transverse-momentum (${p}_{T}$) range of 0.8--10 $\text{GeV}/c$. An excess of direct photons, above prompt-photon production from hard-scattering processes, is observed for ${p}_{T}<6\phantom{\rule{4pt}{0ex}}\text{GeV}/c$. Nonprompt direct photons are measured by subtracting the prompt component, which is estimated as ${N}_{\mathrm{coll}}$-scaled direct photons from $p+p$ collisions at 200 GeV, from the direct-photon spectrum. Results are obtained for $0.8<{p}_{T}<6.0\phantom{\rule{4pt}{0ex}}\text{GeV}/c$ and suggest that the spectrum has an increasing inverse slope from $\ensuremath{\approx}0.2$ to 0.4 $\text{GeV}/c$ with increasing ${p}_{T}$, which indicates a possible sensitivity of the measurement to photons from earlier stages of the evolution of the collision. In addition, like the direct-photon production, the ${p}_{T}$-integrated…

We investigate the weak-interaction-driven bulk-viscous transport properties of npe matter in the neutrino transparent regime. Previous works assumed that the induced bulk viscosity correction to pressure, near beta equilibrium, is linear in deviations from the equilibrium charge fraction. We show that this is not always true for (some) realistic equations of state at densities between one and three times saturation density. This nonlinear nature of the perturbation around equilibrium motivates a far-from-beta-equilibrium description of bulk-viscous transport in neutron star mergers, which can be precisely achieved using a new Israel-Stewart formulation with resummed bulk and relaxation time transport coefficients. The computation of these transport coefficients depends on out-of-beta-equilibrium pressure corrections, which can be computed for a given equation of state. We calculate these coefficients for equations of state that satisfy the latest constraints from multimessenger observations from LIGO/Virgo and NICER detectors. We show that varying the nuclear symmetry energy $J$…

We investigate the $B(E2)$ anomaly observed in neutron-deficient $A\ensuremath{\approx}170$ nuclei by employing an extended consistent-$Q$ Hamiltonian with a third-order term in the interacting boson model. Our analysis demonstrates that including this third-order term accurately describes both the low-lying level energies and $B(E2)$ ratios in $^{168,170,172}\mathrm{Os}$, $^{172,174,176}\mathrm{Pt}$, and $^{166}\mathrm{W}$.

Atomic nuclei near mass 80 with approximately equal numbers of protons and neutrons are known to be strongly deformed while different shapes coexist in the same nucleus. These phenomena have challenged nuclear models but are also an opportunity to test the advances in theoretical approaches. The authors perform $a\phantom{\rule{0}{0ex}}b$-$i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ coupled-cluster calculations for even-even nuclei near neutron-deficient ${}^{80}$Zr, including calculations of $B(E2)$ transitions, using chiral $N\phantom{\rule{0}{0ex}}N$ and $N\phantom{\rule{0}{0ex}}N\phantom{\rule{0}{0ex}}N$ forces. The results adequately describe shape coexistence even if they cannot unambiguously determine ground-state shapes. The calculations are a significant step forward in mass number for $a\phantom{\rule{0}{0ex}}b$-$i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ computations of deformed nuclei.

The evaporation residue (ER) cross sections of $3n$ and $4n$ channels related to the synthesis of a superheavy element (SHE) with the charge number $Z=119$ in the $^{51}\mathrm{V}+^{248}\mathrm{Cm}$ reaction have been calculated by the dinuclear system (DNS) model as a sum of the partial cross sections of the corresponding channels. The angular momentum distribution of the compound nucleus (CN) is estimated by the dynamical trajectory calculations of the capture probability, which is considered as the DNS formation probability. The fusion probability decreases by the increase of the DNS angular momentum due to its influence on the intrinsic fusion barrier ${B}_{\mathrm{fus}}^{*}$. The range ${\ensuremath{\alpha}}_{2}={60}^{\ensuremath{\circ}}$--${70}^{\ensuremath{\circ}}$ of the orientation angle of the axial symmetry axis of the deformed target nucleus $^{248}\mathrm{Cm}$ is favorable for the formation of the CN. The fusion probability decreases at around ${\ensuremath{\alpha}}_{2}={90}^{\ensuremath{\circ}}$ since the number of the partial waves contributing to the capture…

More and more halo nuclei or candidates have been identified or suggested in experiments in recent years. It was declared that the halo structure of $^{22}\mathrm{Al}$ is revealed by the large isospin asymmetry in $^{22}\mathrm{Si}/^{22}\mathrm{O}$ mirror Gamow-Teller transitions [Phys. Rev. Lett. 125, 192503 (2020)]. We highlight that a significant mirror asymmetry already exists between wave functions of the likely unbound nucleus $^{22}\mathrm{Si}$ and the doubly magic nucleus $^{22}\mathrm{O}$, which largely explains the observed asymmetry in the transitions. Furthermore, these transitions involve only the ${1}^{+}$ excited states of the daughter nuclei $^{22}\mathrm{Al}$ and $^{22}\mathrm{F}$. The ${1}^{+}$ state of $^{22}\mathrm{Al}$ cannot be considered a halo state due to its proton-unbound nature. An analysis of the spin parity suggests that a weakly bound $2{s}_{1/2}$ valence proton in the ground state of $^{22}\mathrm{Al}$ is improbable. To investigate the shell structure for the ground state of $^{22}\mathrm{Al}$, we employ the state-of-the-art deformed and triaxial…

A deep neural network (DNN) has been developed to generate the distributions of nuclear charge density, utilizing the training data from the relativistic density functional theory and incorporating available experimental charge radii of 1014 nuclei into the loss function. The DNN achieved a root-mean-square deviation of 0.0193 fm for charge radii on its validation set. Furthermore, the DNN can improve the description in both the tail and central regions of the charge density, enhancing agreement with experimental findings. The model's predictive capability has been further validated by its agreement with recent experimental data on charge radii. Finally, this refined model is employed to predict the charge density distributions in a wider range of nuclide chart, and the parameterized charge densities, charge radii, and higher-order moments of charge density distributions are given, providing a robust reference for future experimental investigations.

We construct efficient emulators for the computation of the infinite nuclear matter equation of state. These emulators are based on the subspace-projected coupled-cluster method for which we here develop a new algorithm called small-batch voting to eliminate spurious states that might appear when emulating quantum many-body methods based on a non-Hermitian Hamiltonian. The efficiency and accuracy of these emulators facilitate a rigorous statistical analysis within which we explore nuclear matter predictions for > 10 6 different parametrizations of a chiral interaction model with explicit Δ -isobars at next-to-next-to leading order. Constrained by nucleon-nucleon scattering phase shifts and bound-state observables of light nuclei up to He 4 , we use history matching to identify nonimplausible domains for the low-energy coupling constants of the chiral interaction. Within these domains we perform a Bayesian analysis using sampling and importance resampling with different likelihood calibrations and study correlations between interaction parameters, calibration observables in light…

The thermal QCD dilepton production rate is calculated at next-to-leading order in the strong coupling and at finite baryon chemical potential. The two-loop virtual photon self-energy is evaluated using finite temperature field theory and combined consistently with the self-energy in the Landau-Pomeranchuk-Migdal regime. We present new results for a dense baryonic plasma. The rates are then integrated using ($3+1$)-dimensional fluid-dynamical simulations calibrated to reproduce hadronic experimental results obtained at the BNL Relativistic Heavy Ion Collider (RHIC) at energies ranging from those of the Beam Energy Scan to $\sqrt{{s}_{NN}}=200$ GeV. We elaborate on the ability of dileptons to relay information about the plasma baryonic content and temperature.

Within the Transport Model Evaluation Project (TMEP), we present a detailed study of the performance of different transport models in $\text{Sn}+\text{Sn}$ collisions at $270A\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$, which are representative reactions used to study the equation of state at suprasaturation densities. We put particular emphasis on the production of pions and $\mathrm{\ensuremath{\Delta}}$ resonances, which have been used as probes of the nuclear symmetry energy. In this paper, we aim to understand the differences in the results of different codes for a given physics model to estimate the uncertainties of transport model studies in the intermediate energy range. Thus, we prescribe a common and rather simple physics model, and follow in detail the results of four Boltzmann-Uehling-Uhlenbeck (BUU) models and six quantum molecular dynamics (QMD) models. The nucleonic evolution of the collision and the nucleonic observables in these codes do not completely converge, but the differences among the codes can be understood as being due to several reasons: the basic differences…

We report the systematic measurement of protons and light nuclei production in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{NN}}\phantom{\rule{0.16em}{0ex}}=\phantom{\rule{0.16em}{0ex}}3\phantom{\rule{0.16em}{0ex}}\mathrm{GeV}$ by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The transverse momentum $({p}_{T})$ spectra of protons $(p)$, deuterons $(d)$, tritons $(t)$, $^{3}\mathrm{He}$, and $^{4}\mathrm{He}$ have been measured from midrapidity to target rapidity for different collision centralities. We present the rapidity and centrality dependence of particle yields $(dN/dy)$, average transverse momentum $(\ensuremath{\langle}{p}_{T}\ensuremath{\rangle})$, yield ratios $(d/p,$ $t/p,^{3}\mathrm{He}/p,$ $^{4}\mathrm{He}/p)$, as well as the coalescence parameters $({B}_{2},$ ${B}_{3})$. The $4\ensuremath{\pi}$ yields for various particles are determined by utilizing the measured rapidity distributions, $dN/dy$. Furthermore, we present the energy, centrality, and rapidity dependence of the compound yield ratios…

We describe an approximation to the in-medium similarity renormalization group (IMSRG) method in which we include the effects of intermediate three-body operators arising within nested commutators. As an initial step, we present the relevant equations for two nested commutators, all of which can be factorized so that the method scales like the standard IMSRG(2) approximation, enabling large-scale calculations. We test the accuracy of this approximation scheme, and apply it to the isotopic chains of carbon, sulfur and nickel isotopic chains. We obtain an improved description of spectroscopy and a reduced dependence on the choice of the valence space. In addition, we provide an explanation of the relative importance of the diagram topologies included, with an eye toward assessing the impact of remaining omitted terms.

We study an approach to simulating the stochastic relativistic advection-diffusion equation based on the Metropolis algorithm. We show that the dissipative dynamics of the boosted fluctuating fluid can be simulated by making random transfers of charge between fluid cells, interspersed with ideal hydrodynamic time steps. The random charge transfers are accepted or rejected in a Metropolis step using the entropy as a statistical weight. This procedure reproduces the expected stress of dissipative relativistic hydrodynamics in a specific (and noncovariant) hydrodynamic frame known as the density frame. Numerical results, both with and without noise, are presented and compared to relativistic kinetics and analytical expectations. An all order resummation of the density frame gradient expansion reproduces the covariant dynamics in a specific model. In contrast to all other numerical approaches to relativistic dissipative fluids, the dissipative fluid formalism presented here is strictly first order in gradients and has no nonhydrodynamic modes. The physical naturalness and simplicity of…

The influence of the daughter nuclei deformations on the α decay's half-life is modeled by adding the term depending on the quadrupole deformation parameter value to the empirical relations for the α -decay half-lives. It is shown that the addition of the deformation-dependent term led to a better description of the experimental data by the empirical expressions for the half-lives of the α decay than the ones without it. A new empirical expression for a description of the α -decay half-lives is proposed. The empirical relation for the α decay half-lives for the transitions from the ground state to the ground state and the lowest 2 + state of the even-even nuclei is discussed. Published by the American Physical Society 2024

We analyze the isospin equilibration properties of neutrinoless nuclear ($npe$) matter in the temperature and density range that is relevant to neutron star mergers. Our analysis incorporates neutrino-transparency corrections to the isospin (``beta'') equilibrium condition which become noticeable at $T\ensuremath{\gtrsim}1\phantom{\rule{0.16em}{0ex}}\text{MeV}$. We find that the isospin relaxation rate rises rapidly as temperature rises, and at $T\ensuremath{\approx}5\phantom{\rule{0.16em}{0ex}}\text{MeV}$ it is comparable to the timescale of the density oscillations that occur immediately after the merger. This produces a resonant peak in the bulk viscosity at $T\ensuremath{\approx}5\phantom{\rule{0.16em}{0ex}}\text{MeV}$, which causes density oscillations to be damped on the timescale of the merger. Our calculations suggest that isospin relaxation dynamics may also be relevant when neutrinos are treated more accurately via neutrino transport schemes.

The binding energy or mass is one of the most fundamental properties of an atomic nucleus. Precise binding energies are vital inputs for many nuclear physics and nuclear astrophysics studies. However, due to the complexity of atomic nuclei and the nonperturbative strong interaction, up to now, no conventional physical model can describe nuclear binding energies with a precision below 0.1 MeV, the accuracy needed by nuclear astrophysical studies. In this work, artificial neural networks (ANNs), the so-called ``universal approximators'', are used to calculate nuclear binding energies. We show that the ANN can describe all the nuclei in AME2020 with a root-mean-square deviation (RMSD) around 0.2 MeV, better than the best macroscopic-microscopic models, such as FRDM and WS4. The success of the ANN is mainly due to the proper and essential input features we identify, which contain the most relevant physical information, i.e., shell, paring, and isospin-asymmetry effects. We show that the well-trained ANN has excellent extrapolation ability and can predict binding energies for those…

Nuclear entanglement is a flagship in the interdisciplinary direction of nuclear physics and quantum information science. Spin entanglement, a special kind of nuclear entanglement, is ubiquitous in nuclear structures and dynamics. Based on the idea of quantum state tomography, the problem of experimental determination of spin entanglement of two-nucleon pure states is studied directly within the scope of nuclear physics. It is shown that the amount of spin entanglement can be obtained by measuring three spin polarizations of one nucleon in polarization experiments. The errors from imperfect preparation of nucleon pairs are also analyzed. This work not only complements the existing literature of nuclear entanglement but also provides new opportunities for nuclear physics with polarized particles.

The microscopic framework of time-dependent covariant density functional theory is applied to study multinucleon transfer reactions with transfer probabilities calculated using the particle number projection method. It is found that similar total cross sections are obtained with two different relativistic density functionals, PC-PK1 and DD-ME2, as well as with the Skyrme functional SLy5 in a previous study, for multinucleon transfer in the reactions: $^{40}\mathrm{Ca}+^{124}\mathrm{Sn}$ at ${E}_{\mathrm{lab}}=170\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$, $^{40}\mathrm{Ca}+^{208}\mathrm{Pb}$ at ${E}_{\mathrm{lab}}=249\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$, and $^{58}\mathrm{Ni}+^{208}\mathrm{Pb}$ at ${E}_{\mathrm{lab}}=328.4\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$. We report the microscopic calculation of total cross sections for the reactions: $^{40}\mathrm{Ar}+^{208}\mathrm{Pb}$ at ${E}_{\mathrm{lab}}=256\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$ and $^{206}\mathrm{Pb}+^{118}\mathrm{Sn}$ at ${E}_{\mathrm{lab}}=1200\phantom{\rule{0.16em}{0ex}}\mathrm{MeV}$. Compared to the…

We present calculations of the $^{40}\mathrm{Ca}$ transverse response function obtained from coupled-cluster theory used in conjunction with the Lorentz integral transform method. We employ nuclear forces derived at next-to-next-to leading order in chiral effective field theory with and without $\mathrm{\ensuremath{\Delta}}$ degrees of freedom. We first benchmark this approach on the $^{4}\mathrm{He}$ nucleus and compare both the transverse sum rule and the response function to earlier calculations based on different methods. As expected from the power counting of the chiral expansion of electromagnetic currents and from previous studies, our results retaining only one-body term underestimate the experimental data for $^{4}\mathrm{He}$ by about $20%$. However, when the method is applied to $^{40}\mathrm{Ca}$ at the same order of the expansion, response functions do not lack strength and agree well with the world electron scattering data. We discuss various sources of theoretical uncertainties and comment on the comparison of our results with the available experiments.

We study diffractive vector meson production in ultraperipheral collisions of heavy nuclei, utilizing a theoretical framework based on the color glass condensate formalism. We focus on $\mathrm{Au}+\mathrm{Au}, \mathrm{U}+\mathrm{U}, \mathrm{Ru}+\mathrm{Ru}, \mathrm{Zr}+\mathrm{Zr}$, and $\mathrm{Pb}+\mathrm{Pb}$ collisions, examining the transverse momentum dependence of vector meson production cross-sections and $\mathrm{cos}(2\mathrm{\ensuremath{\Delta}}\mathrm{\ensuremath{\Phi}})$ asymmetries in the decay product distributions to explore the role of nuclear geometry. The angular modulation is due to the linear polarization of the incoming photons and quantum interference effects. We extract nuclear radii and find them to be consistent with experimental data from the STAR collaboration. The amplitudes of the $\mathrm{cos}(2\mathrm{\ensuremath{\Delta}}\mathrm{\ensuremath{\Phi}})$ modulation in the cross-section and the extracted radii depend on the nuclear geometry. This dependence is dominated by the geometry-dependent variation of the minimum impact parameter required for…

We explore the impact of retaining three-body operators within the in-medium similarity renormalization group (IMSRG), as well as various approximations schemes. After studying two toy problems, identical fermions with a contact interaction and the Lipkin-Meshkov-Glick model, we employ the valence-space formulation of the IMSRG to investigate the even-$A$ carbon isotopes with a chiral two-body potential. We find that retaining only those commutators expressions that scale as ${N}^{7}$ provides an excellent approximation of the full three-body treatment.

We propose an algebraic approach to elucidate the dynamic characteristics of triaxial rotor modes in nuclei by mapping a triaxial rotor Hamiltonian to the interacting boson model one within a finite-$N$ framework. Our method unveils striking features not observed in conventional modes, exemplified by the $B(E2)$ anomaly, characterized by $B(E2;{4}_{1}^{+}\ensuremath{\rightarrow}{2}_{1}^{+})/B(E2;{2}_{1}^{+}\ensuremath{\rightarrow}{0}_{1}^{+})<1$. Using specific examples, we demonstrate that the peculiar properties of low-lying states in both neutron-rich and neutron-deficient Os nuclei can be comprehensively understood through the proposed Hamiltonian, which incorporates both rigid and soft triaxial rotor modes. This algebraic method not only offers fresh insights into triaxial dynamics but also showcases its capability in uncovering emergent exotic collective modes in nuclear structure.

$A\phantom{\rule{0}{0ex}}b$-$i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ calculations of atomic nuclei have revolutionized nuclear structure physics. Yet challenges remain, not least the reliable calculation of nuclear radii. In a concurrent development, modern machine-learning algorithms have excelled in a variety of computational tasks such as pattern recognition and interpolation. The authors have applied artificial neural networks (ANNs) to the extrapolation of no-core shell model calculations to infinite model spaces, effectively circumventing their computational limitations. In particular, the results show that min-max normalization, a common technique in machine learning, leads to the best results for radii. These advances offer hope that the ANN architecture is capable of handling other observables such as electromagnetic moments and transition strengths.

The predictive power of the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with density functional PC-PK1 is demonstrated for superheavy region ($101\ensuremath{\leqslant}Z\ensuremath{\leqslant}120$) by comparing with available experimental and evaluated data from AME2020. The DRHBc theory predicts 93 bound nuclei beyond the drip line $N=258$ in the region of $106\ensuremath{\leqslant}Z\ensuremath{\leqslant}112$, which form a stability peninsula. The odd-even differences between $\mathrm{odd}\text{\ensuremath{-}}N$ and even-$N$ nuclei are remarkable in the peninsula; the one-neutron separation energy of an $\mathrm{odd}\text{\ensuremath{-}}N$ nucleus is smaller than those of its neighboring even-$N$ nuclei due to the blocking effect, and as a result the number of bound $\mathrm{odd}\text{\ensuremath{-}}N$ nuclei is less than that of bound even-$N$ nuclei. The deformation effect is indispensable for the re-entrant stability beyond the drip line by significantly affecting the structure of single-particle levels around the Fermi energy. The interplay between…

We investigate $\ensuremath{\alpha}$-decay half-lives for 74 $\ensuremath{\le}$ Z $\ensuremath{\le}$ 92 even-even nuclei within the semiclassical WKB approximation in deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc). The $\ensuremath{\alpha}$-particle preformation factors are estimated from cluster-formation model using both empirical AME2020 binding energies and numerical ones obtained by a deep neural network (DNN) study in which the available DRHBc binding energies are used as training set. We find that our estimated $\ensuremath{\alpha}$-decay half-lives are qualitatively in agreement with experimental results. We also compare our results with the empirical formulas, ZZCW and UNIV. Based on these observation, we extend our predictions of $\ensuremath{\alpha}$-decay half-lives for the isotopes whose experimental data are not available.

The compositeness of weakly bound states is discussed using the effective field theory from the viewpoint of the low-energy universality. We introduce a model with coupling of the single-channel scattering to the bare state, and study the compositeness of the bound state by varying the bare state energy. In contrast to the naive expectation that the near-threshold states are dominated by the molecular structure, we demonstrate that a noncomposite state can always be realized even with a small binding energy. At the same time, however, it is shown that a fine tuning is necessary to obtain the noncomposite weakly bound state. In other words, the probability of finding a model with the composite dominant state becomes larger with the decrease of the binding energy, in accordance with the low-energy universality. For the application to exotic hadrons, we then discuss the modification of the compositeness due to decay and coupled-channels effects. We quantitatively show that these contributions suppress the compositeness, because of the increase of the fraction of other components.…

Covariant density functional theory is solved in 3D lattice space by implementing the preconditioned conjugate gradient method with a filtering function. It considerably improves the computational efficiency compared to the previous inverse Hamiltonian method (IHM). This new method is then applied to explore the tetrahedral shape of $^{110}\mathrm{Zr}$ in the full deformation space. Although the ground-state energy and deformation are consistent with the previous study, the pear-shaped isomeric state is significantly lowered in energy. The energy difference between the two states is only 0.07 MeV, indicating an interesting possible shape coexistence in $^{110}\mathrm{Zr}$. This effect is analyzed with the microscopic evolution of the single-particle levels near the Fermi surface driven by the deformation.

Background: Masses of neutron-rich exotic nuclei are important for both nuclear physics and nuclear astrophysics, yet most of them remain beyond the current experimental capabilities. The relativistic continuum Hartree-Bogoliubov (RCHB) theory has achieved great success in the study of exotic nuclei. In the first paper of this series [Phys. Rev. C 109, 024310 (2024)], the kernel ridge regression (KRR) approach has been employed to refine the RCHB mass model, and the predictive power has been validated through comparison with the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) for even-even nuclei. Recently, the mass data for even-odd nuclei have been released by the DRHBc Mass Table Collaboration [At. Data Nucl. Data Tables 158, 101661 (2024)]. The KRR approach has been extended to incorporate odd-even effects [Phys. Lett. B 819, 136387 (2021)], thereby enhancing its capability in nuclear mass predictions.Purpose: The aim of this work is to combine the RCHB mass model and the extended KRR approach with odd-even effects (KRRoe) to improve the predictions of…

The state-of-the-art in the modeling and analysis of relativistic heavy-ion collisions involves multistage approaches to simulate the evolving strongly interacting matter and uses Bayesian analysis to obtain statistically relevant physical quantities. This work features a (3+1)D model applied to collision energies lower than those considered so far to explore the full range of the RHIC beam energy scan. This enables an exploration of the behavior of QCD at large baryon chemical potentials. The results of such comprehensive and systematic phenomenological studies have promise to advance knowledge of QCD in extreme conditions.

The $\ensuremath{\gamma}$-ray strength functions (GSFs) and nuclear level densities (NLDs) below the neutron threshold have been extracted for $^{111--113,116--122,124}\mathrm{Sn}$ from particle-$\ensuremath{\gamma}$ coincidence data with the Oslo method. The evolution of bulk properties of the low-lying electric dipole response has been investigated on the basis of the Oslo GSF data and results of a recent systematic study of electric- and magnetic dipole strengths in even-even Sn isotopes with relativistic Coulomb excitation. The obtained GSFs reveal a resonance-like peak on top of the tail of the isovector giant dipole resonance centered at $\ensuremath{\approx}8$ MeV and exhausting $\ensuremath{\approx}2%$ of the classical Thomas-Reiche-Kuhn (TRK) sum. For mass numbers $\ensuremath{\ge}118$ the data suggest also a second peak centered at $\ensuremath{\approx}6.5$ MeV. It corresponds to 0.1%--0.5% of the TRK sum rule and shows an approximate linear increase with the mass number. In contrast with predictions of the relativistic quasiparticle random-phase and time-blocking…

Background: Multinucleon transfer (MNT) reactions are considered now as a possible tool to produce new isotopes of heavy and superheavy elements.Purpose: Experimental study of MNT fragments formed in the $^{136}\mathrm{Xe}+^{238}\mathrm{U}$ reaction at $^{136}\mathrm{Xe}$ beam energy of 1.11 GeV and comparison with theoretical calculations.Methods: Primary and secondary mass and energy distributions of projectilelike fragments (PLF) formed in the $^{136}\mathrm{Xe}+^{238}\mathrm{U}$ reaction have been experimentally investigated independently and in coincidence with survived heavy targetlike fragments (TLF) using the CORSET setup. Since the heavy fragments formed in the reactions are highly excited the masses, energies, and angles of both fragments as products of the sequential fission of heavy MNT fragments have been measured.Results: The cross sections for PLFs at $27.{2}^{\ensuremath{\circ}}\ensuremath{\le}{\ensuremath{\theta}}_{\mathrm{lab}}\ensuremath{\le}32.{8}^{\ensuremath{\circ}}$ along with survived TLFs and TLFs undergoing fission have been obtained. The mass loss during…

We investigate the nuclear symmetry energy and neutron star properties using a Bayesian analysis based on constraints from different chiral effective field theory calculations using new energy density functionals that allow for large variations at high densities. Constraints at high densities are included from observations of GW170817 and from NICER. In particular, we show that both NICER analyses lead to very similar posterior results for the symmetry energy and neutron star properties when folded into our equation-of-state framework. Using the posteriors, we provide results for the symmetry energy and the slope parameter, as well as for the proton fraction, the speed of sound, and the central density in neutron stars. Moreover, we explore correlations of neutron star radii with the pressure and the speed of sound in neutron stars. Our 95% credibility ranges for the symmetry energy S v , the slope parameter L , and the radius of a 1.4 M ⊙ neutron star, R 1.4 , are S v = ( 30.6 – 33.9 ) MeV , L = ( 43.7 – 70.0 ) MeV , and R 1.4 = ( 11.6 – 13.2 ) km . Our analysis for the proton…