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Nuclear Theory·nucl-th

Wednesday·October 18, 2023

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    Electric dipole polarizability of low-lying excited states in atomic nuclei

    José Nicolás Orce · Cebo Ngwetsheni

    Novel equations for the electric dipole polarizability of low-lying excited states in atomic nuclei -- and the related moment of the total photo-absorption cross section, -- are inferred in terms of electric dipole and quadrupole matrix elements. These equations are valid for arbitrary angular momenta of the initial/ground and final/excited states and have been exploited in fully converged 1 shell-model calculations of selected {\it p-} and {\it sd-}shell nuclei that consider configuration mixing; advancing previous knowledge from O to Ar, where thousands of electric dipole matrix elements are computed from isovector excitations which include the giant dipole resonance region. Our results are in reasonable agreement with previous shell-model calculations and follow -- except for Li and O -- Migdal's global trend provided by the combination of the hydrodynamic model and second-order non-degenerate perturbation theory. Discrepancies in Li and O arise as a result of the presence of -cluster configurations in odd-mass nuclei, whereas the disagreement in O comes from the mixing of intruder states, which is lacking in the shell-model interactions. More advanced \emph{ab initio} calculations of the dipole polarizability for low-lying excited states covering all the isovector states within the giant dipole resonance region are missing and could be very valuable to benchmark the results presented here and shed further light on how atomic nuclei polarize away from the ground state

    nucl-thnucl-exJ.Phys.G(2024)·4 citations
  2. 02

    Viscosities of the Baryon-Rich Quark-Gluon Plasma from Beam Energy Scan Data

    Chun Shen🇺🇸 · Björn Schenke🇺🇸 · Wenbin Zhao🇺🇸

    This work presents the first Bayesian inference study of the (3+1)D dynamics of relativistic heavy-ion collisions and Quark-Gluon Plasma (QGP) viscosities using an event-by-event (3+1)D hydrodynamics + hadronic transport theoretical framework and data from the Relativistic Heavy Ion Collider (RHIC) Beam Energy Scan program. Robust constraints on initial state nuclear stopping and the baryon chemical potential-dependent shear viscosity of the produced quantum chromodynamic (QCD) matter are obtained. The specific bulk viscosity of the QCD matter is found to exhibit a preferred maximum around GeV. This result allows for the alternative interpretation of a reduction (and/or increase) of the speed of sound relative to that of the employed lattice-QCD based equation of state (EOS) for net baryon chemical potential GeV.

    nucl-thhep-phnucl-exPRL(2024)·42 citations
  3. 03

    A Data-Driven Density Functional Model for Nuclear Systems

    Zu-Xing Yang · Xiao-Hua Fan · Zhi-Pan Li · Haozhao Liang

    Through ensemble learning with multitasking and complex connection neural networks, we aggregated nuclear properties, including ground state charge radii, binding energies, and single-particle state information obtained from the Kohn-Sham auxiliary single-particle systems. Compared to traditional density functional theory, our model can more accurately characterize nuclear ground state information. Aiming at binding energy, the root mean square error is reduced to 450 keV. Although the complexity involving the nuclear interaction is skipped, the model has not completely devolved into a black box. Leveraging the correlation between densities and binding energies, we calculate the neutron skin thickness of Pb to be 0.223 fm. This model will advance our understanding of nuclear properties and accelerate the integration of machine learning into modern nuclear physics.

    nucl-thnucl-exPRC(2024)·3 citations
  4. 04

    -dependence of jet observables with JEWEL+v-USPhydro

    Leonardo Barreto🇧🇷 · Fabio M. Canedo🇧🇷 · Maria M. M. Paulino🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Jorge Noronha🇺🇸 · Marcelo G. Munhoz🇧🇷

    The -dependence of jet observables provides a new tool in understanding the interplay between the jet energy-loss mechanism and medium response in heavy-ion collisions. This work applies the Monte Carlo events generator JEWEL and PYTHIA, coupled with initial conditions and the state-of-the-art (2+1)D v-USPhydro, for the simulation of jet distributions and substructure observables for lead-lead collisions at LHC energy scales. We present the jet nuclear modification and anisotropic flow coefficients varying the jet cone radius , in the context of anti- jets, in addition to leading subjet fragmentation. The calculations indicate the impacts of the hydrodynamic evolution and weakly-coupled medium response, given by recoils, on the distributions. Results are compared to experimental data in a wide range of jet and collision centrality, and displayed along large jets () predictions.

    nucl-thhep-phPoS(2024)·0 citations
  5. 05

    Conservation Laws and Hydrodynamics

    Sangyong Jeon🇨🇦

    Recent years have seen much development in analyzing the structure of relativistic hydrodynamics. In this proceeding, some of the developments are highlighted including issues related to pseudo-gauge transformations and spin hydrodynamics.

    nucl-thEPJ Web Conf.(2023)·4 citations
  6. 06

    Is enhancement in heavy ion collisions a signature of chiral symmetry restoration?

    Haesom Sung🇰🇷 · Sungtae Cho🇰🇷 · Che Ming Ko🇺🇸 · Su Houng Lee🇰🇷 · Sanghoon Lim🇰🇷

    We extend the recent study of enhancement as a signature of chiral symmetry restoration in heavy ion collisions at the Large Hadron Collider (LHC) via the kinetic approach to include the effects due to non-unity hadron fugacities during the evolution of produced hadronic matter and the temperature-dependent mass. Although the effect of non-unity fugacity only slightly reduces the enhancement due to chiral symmetry restoration, the inclusion of the temperature-dependent mass leads to a substantial reduction in the enhancement. However, the final ratio in peripheral collisions still shows a more than factor of two enhancement compared to the case without chiral symmetry restoration and thus remains a good signature for chiral symmetry restoration in the hot dense matter produced in relativistic heavy ion collisions.

    nucl-thhep-phPoS(2025)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE