Nuclear Theory·nucl-th

Tuesday·October 22, 2024

13 papers—8 primary·5 cross-listed

01
Regulator-independent equations of state for neutron stars generated from first principles
J. M. Alarcón🇪🇸 · E. Lope-Oter🇪🇸 · J. A. Oller🇪🇸
We study the equation of state (EoS) of a neutron star (NS) accounting for new advances. In the low energy density, $n \leq 0.1 n_{s}$ , with $n_{s}$ the saturation density, we use a new pure neutron matter EoS that is regulator independent and expressed directly in terms of experimental nucleon-nucleon scattering data. In the highest-density domain our EoS's are matched with pQCD to $O (α_{s}^{3})$ . First principles of causality, thermodynamic consistency and stability are invoked to transit between these two extreme density regimes. The EoS's are further constrained by the new measurements from PREX-II and CREX on the symmetry energy ( $S_{0}$ ) and its slope ( $L$ ). In addition, we also take into consideration the recent experimental measurements of masses and radii of different NSs and tidal deformabilities. A band of allowed EoS's is then obtained. Interestingly, the resulting values within the band for $S_{0}$ and $L$ are restricted with remarkably narrower intervals than the input values, with $32.9 \leq S_{0} \leq 39.5 MeV$ and $37.3 \leq L \leq 69.0 MeV$ at the 68\% CL. The band of EoS's constructed also allows possible phase transitions (PTs) for NS masses above 2.1~ $M_{⊙}$ at 68\% CL for $n > 2.5 n_{s}$ . We find both long and short coexistence regions during the PT, corresponding to first and second order PTs, respectively. We also generate the band of EoS's when excluding the astrophysical observables. This is of interest to test General Relativity and modified theories of gravity. Our band of EoS's for NSs can be also used to study other NS properties and dark matter capture in NS.
nucl-thastro-ph.HEhep-phPRD(2025)·10 citations
02
Pair momentum dependence of tilted source in heavy ion collisions
Yevheniia Khyzhniak🇺🇸 · Michael Annan Lisa🇺🇸
In non-central heavy-ion collisions, the particle-emitting source can be tilted away from the beam direction, an effect that becomes particularly significant at collision energies of a few GeV and lower. This phenomenon, manifest itself in many observables such as directed flow, polarization, and vorticity, is therefore important to investigate. In this paper, we study the consistency between the tilt extracted directly from the freeze-out distribution of pions and the tilt parameter obtained using the azimuthally sensitive femtoscopy (asHBT) method. Using the UrQMD model, we demonstrate a strong dependence of the tilt parameter extracted with asHBT on the momentum of the particle pair. Considering the experimental challenges in accessing low particle momenta - where the tilt parameter extracted with asHBT closely matches the tilt of the freeze-out distribution of pions - we propose an exponential extrapolation method to obtain the tilt of the entire freeze-out distribution. This approach aims to enhance the accuracy of experimental measurements of tilt in non-central heavy-ion collisions.
nucl-thhep-phnucl-exPRC(2025)·5 citations
03
Relativistic second-order spin hydrodynamics: A Kubo-type formulation for the quark-gluon plasma
Duan She🇨🇳 · Yi-Wei Qiu🇨🇳 · Defu Hou🇨🇳
Building upon Zubarev's nonequilibrium statistical operator formalism, we derive a relativistic canonical-like second-order spin hydrodynamics for two power-counting schemes. We obtain comprehensive second-order expressions for dissipative fluxes, including the shear stress tensor, bulk viscous pressure, charge-diffusion currents, rotational stress tensor, boost heat vector, and spin tensor-related dissipative flux. By introducing novel transport coefficients and expressing them in terms of equilibrium correlation functions, we establish new Kubo-type formulas for second-order transport. Our findings have significant implications for understanding the collective spin dynamics of strongly interacting matter and provide a robust theoretical basis for future experimental and theoretical studies.
nucl-thPRD(2025)·17 citations
04
Superheavy Magic Nuclei: Ground-State Properties, Bubble Structure and {\alpha}-Decay Chains
R. Sharma · A. Jain · M. Kumawat · J. K. Deegwal · Abdul Quddus · G. Saxena
A systematic investigation of superheavy nuclei in the isotopic chains of proton numbers Z=106, 114, 120, and 126 together with isotonic chains of neutron numbers N=162, 172, and 184 is presented in the theoretical framework of relativistic mean-field density functionals based on density-dependent meson-nucleon couplings. Ground-state properties, including binding energy, shape, deformation, density profile, and radius, are estimated to provide compelling evidence of magicity in these even-even nuclei, aligning with the concept of the 'island of stability'. The analysis reveals central depletion in the charge density, indicating a bubble-like structure, primarily attributed to the substantial repulsive Coulomb field and the influence of higher l-states. A thorough examination of potential decay modes, employing various semi-empirical formulas, is presented. The probable alpha-decay chains are evaluated, demonstrating excellent agreement with available experimental data
nucl-thNPA(2025)·2 citations
05
Test of $T$ -invariance in scattering of polarized protons on tensor-polarized deuterons at energies of the NICA SPD
Yu.N. Uzikov🇷🇺 · M.N. Platonova🇷🇺
The effect of violation of $T$ -invariance, provided that $P$ -parity is preserved, is given by the total cross section of the interaction of a vector-polarized particle with a tensor-polarized target. A formalism for calculating this effect developed previously and based on the spin-dependent Glauber theory of elastic $p d$ scattering is used here to calculate the effect under discussion in the range of collision energies corresponding to the invariant mass of the $pN$ system $s_{pN} = 5$ -- $30$ GeV. The spin-dependent amplitudes of elastic $pN$ scattering required for this calculation are taken from existing phenomenological models for $pN$ scattering in the energy region considered.
nucl-thhep-exhep-phnucl-exPhys.Part.Nucl.(2025)·2 citations
06
Shell quenching in nuclear charge radii based on Monte Carlo dropout Bayesian neural network
Zhen-Yan Xian · Yan Ya · Rong An
Charge radii can be generally used to encode information about various fine structures of finite nuclei. In this work, a constructed Bayesian neural network based on the Monte Carlo dropout approach is proposed to accurately describe the charge radii of nuclei with proton number $Z \geq 20$ and mass number $A \geq 40$ . More motivated underlying mechanisms are incorporated into this combined model in addition to the basic building blocks with the specific number of protons and neutrons, which naturally contain the pairing effect, the isospin effect, the shell closure effect associated with the Casten factor $P$ , the valence neutrons, the valence protons, the quadrupole deformation $β_{20}$ , the high order hexadecapole deformation $β_{40}$ , and the local shape staggering effect of $^{181, 183, 185}$ Hg. To avoid the distorted cases of the traditional Casten factor at the fully filled shells, the modified Casten factor $P^{*}$ is introduced into the input structure parameter sets. The standard root-mean-square deviation is reduced to $0.0084$ fm for the training data set and $0.0124$ fm for the validation data set with the modified Casten factor $P^{*}$ . Meanwhile, the shell closure effect of nuclear charge radii can be reproduced remarkably well. We have successfully demonstrated the ability of this constructed model to significantly increase the accuracy in predicting the nuclear charge radii.
nucl-thnucl-exPLB(2025)·6 citations
07
The nuclear symmetry energy and the neutron skin thickness in nuclei
G. F. Burgio · H. C. Das · I. Vidana (INFN Sezione di Catania)
We investigate possible correlations between the stiffness of the symmetry energy at saturation density, the so-called $L$ parameter, and the neutron skin thickness of $^{48}$ Ca and $^{208}$ Pb, for which the recent measurements from the CREX and PREX I+II experiments at the Thomas Jefferson Laboratory became available. We choose an ensemble of nucleonic equations of state (EoS) derived within microscopic (BHF, Variational, AFDMC) and phenomenological (Skyrme, RMF, DD-RMF) approaches. They are all compatible with the laboratory nuclear collisions data and with current observations of neutron stars (NS) mass and the tidal polarizability of a 1.4 $M_{⊙}$ NS, as deduced from the GW170817 event. We find some degree of correlation between the $L$ parameter and the neutron skin thickness whereas a much weaker correlation does exist with the tidal polarizability and the symmetry energy at saturation density. However, some EoS which are able to explain the CREX experimental data, are not compatible with the PREX I+II data, and viceversa. We confirm the results previously obtained with a different set of EoS models, and find a possible tension between the experimental data and the current understanding of the nuclear EoS.
nucl-thFront.Astron.Space Sci.(2024)·6 citations
08
Heavy Quarkonium-nuclear bound states within a generalized linear sigma model
Arpita Mondal🇮🇳 · Amruta Mishra🇮🇳
We estimate the binding energies of charmonium ( $J / ψ$ , $ψ (2 S)$ , $ψ (1 D)$ , $χ_{c 0}$ , $χ_{c 1}$ , $χ_{c 2}$ ) and bottomonium ( $Υ (1 S)$ , $Υ (2 S)$ , $Υ_{2} (1 D)$ , $χ_{b 0}$ , $χ_{b 1}$ , $χ_{b 2}$ ) states bound in various nuclei ( $^{4} He$ , $^{12} C$ , $^{16} O$ , $^{40} Ca$ , $^{90} Zr$ , and $^{208} Pb$ ) using the quarkonia-nuclei potentials obtained from their mass shifts in nuclear matter within the generalized linear sigma model. In the absence of light partons in heavy quarkonia, at the tree level, the medium modifications are driven by the gluon condensate, which is simulated within this model through a scalar dilaton field, $χ$ , by introducing broken scale invariance of QCD. Our study shows that charmonium states bind more deeply with the atomic nuclei as compared to bottomonium states, providing a better probe for nuclear medium effects. Such bound states' investigations are particularly interesting for the upcoming J-PARC-E29, $P ˉ ANDA$ @FAIR, and CEBAF@JLab experiments. The mass shifts of the heavy quarkonium states in hot isospin asymmetric nuclear matter are investigated and are observed to receive an appreciable medium modification. These medium effects are anticipated at FAIR@GSI, where such neutron-rich hot nuclear matter is expected to be produced.
nucl-thhep-ph1 citation
09
Beauty hadron production in high energy proton-proton and heavy-ion collisions in the EPOS4HQ framework
J. Zhao🇫🇷 · J. Aichelin🇩🇪 · P.B. Gossiaux🇫🇷 · K. Werner🇫🇷
Charmed hadron observables from the RHIC to LHC energies have been very successfully described with the recently advanced EPOS4HQ event generator. Here we extend this investigation to the production of beauty hadrons in proton-proton (pp) and heavy ion (HI) collisions
↳ hep-phnucl-thPoS(2025)·1 citation
10
Quark mass effects in octet baryon magnetic polarisabilities via lattice QCD
Thomas Kabelitz🇦🇺 · Waseem Kamleh🇦🇺 · Derek Leinweber🇦🇺
The quark mass dependence of octet baryon magnetic polarisabilities is examined at the level of individual quark-sector contributions in the uniform background-field approach of lattice QCD. The aim is to understand the direct impact of increasing the mass of a quark flavour on the magnetic polarisability and indirect or environmental effects associated with changing the mass of spectator quarks, insensitive to the background magnetic field. Noting the need to set the electric charge of some quark flavours to zero, a fractionally charged baryon formalism is introduced. We find that increasing the mass of the charged quark flavour directly causes its contribution to the magnetic polarisability to decrease. However, increasing the mass of the spectator quark flavour indirectly acts to increase the magnetic polarisability. To gain a deeper understanding of these effects, we evaluate the predictions of the constituent quark model in this context. While the model provides a compelling explanation for the environmental effect of varying the spectator quark mass, an explanation of the direct mass dependence is more complicated as competing factors combine in the final result. The lattice results indicate the key factor is a reduction in the constituent quark magnetic moment with increasing quark mass, as it governs the strength of the magnetic transition to the nearby decuplet baryon.
↳ hep-lathep-phnucl-thPRD(2025)·1 citation
11
Probing the onset of hydrodynamization in peripheral p-Pb collisions at $s_{N N} =$ 5.02 TeV
Nikhil Hatwar🇮🇳 · Sadhana Dash🇮🇳 · Basanta Kumar Nandi🇮🇳
An attempt has been made to estimate the minimum size of the de-confined matter of Quark-Gluon Plasma (QGP) in small systems like p-Pb system that could be satisfactorily modeled with low-order hydrodynamics. The variation of second order transport coefficient of second order relativistic viscous hydrodynamics, the shear relaxation time has been utilized to study the sensitivity of experimental observables like elliptic flow coefficient. A representative system of p-Pb collisions at $s_{N N} =$ 5.02 TeV, simulated with the state-of-art framework of JETSCAPE event generator was used to study the variation of elliptic flow coefficient for peripheral collisions. The soft sector dynamics was simulated using an initial condition, a pre-equilibrium stage, hydrodynamics and a hadron afterburner. The transverse momentum spectra and rapidity distribution was obtained for light flavored hadrons and compared with the experimental data. The increase in elliptic flow fluctuations indicate breakdown of fluid behavior at $d N / d y \approx 14$ for p-Pb collision at $s_{N N} =$ 5.02 TeV.
↳ hep-phnucl-th1 citation
12
Kaons and antikaons in isospin asymmetric dense resonance matter at finite temperature
Manpreet Kaur🇮🇳 · Arvind Kumar🇮🇳
We study the in-medium properties of kaons and antikaons in isospin asymmetric hot and dense resonance matter within the chiral SU(3) hadronic mean field model. Along with nucleons and hyperons, the interactions of $K$ and $K ˉ$ mesons with all decuplet baryons ( $Δ^{++, +, 0, -}, Σ^{*\pm, 0}, Ξ^{* 0, -}, Ω^{-}$ ) are explicitly considered in the dispersion relations. The properties of mesons in the chiral SU(3) model are modified at finite density and temperature of asymmetric resonance matter through the exchange of scalar fields $σ, ζ$ and $δ$ and the vector fields $ω, ρ$ and $ϕ$ . The presence of resonance baryons in the medium at finite temperature is observed to modify significantly the effective masses of $K$ and $K ˉ$ mesons. We also calculated the optical potentials of kaons and antikaons as a function of momentum in resonance matter. The present study of in-medium masses and optical potentials of kaons and antikaons will be important for understanding the experimental observables from the heavy-ion collision experiments where hot and dense matter may be produced. Our results indicate that when resonance baryons are present within the medium at finite baryonic density, the mass reduction of kaons and antikaons becomes more pronounced as the temperature of the medium increases from zero to 100 and 150 MeV. The study of the optical potentials of kaons and antikaons reveals a stronger correlation with strangeness fraction compared to isospin asymmetry.
↳ hep-phnucl-thPRD(2024)·9 citations
13
Locating the QCD critical point through contours of constant entropy density
Hitansh Shah🇺🇸 · Mauricio Hippert🇧🇷 · Jorge Noronha🇺🇸 · Claudia Ratti🇺🇸 · Volodymyr Vovchenko🇺🇸
We propose a new method to investigate the existence and location of the conjectured high-temperature critical point of strongly interacting matter via contours of constant entropy density. By approximating these lines as a power series in the baryon chemical potential $μ_{B}$ , one can extrapolate them from first-principle results at zero net-baryon density, and use them to locate the QCD critical point, including the associated first-order and spinodal lines. As a proof of principle, we employ currently available continuum-extrapolated first-principle results from the Wuppertal--Budapest collaboration to find a critical point at a temperature and a baryon chemical potential of $T_{c} = 114.3 \pm 6.9$ MeV and $μ_{B, c} = 602.1 \pm 62.1$ MeV, respectively. We advocate for a more precise determination of the required expansion coefficients via lattice QCD simulations as a means of pinpointing the location of the critical endpoint in the phase diagram of strongly interacting matter.
↳ hep-phhep-latnucl-exnucl-thPRC(2026)·55 citations

Affiliations

first authorsco-authorsvia INSPIRE