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Nuclear Theory·nucl-th

Wednesday·December 8, 2021

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    Fate of Multiparticle Resonances: From -Balls to He Droplets

    Dam Thanh Son🇺🇸 · Mikhail Stephanov🇺🇸 · Ho-Ung Yee🇺🇸

    We consider a system of nonrelativistic particles which form a near-threshold resonance. Assuming no subset of these particles can form a bound state, the resonance can only decay through an "explosion" into particles. We show that the decay width of the resonance scales as in the limit when the energy of the resonance goes to zero, where is the ground state energy of a system of particles in a spherical harmonic trap with unit frequency. The formula remains valid when some pairs of final particles have zero-energy -wave resonance, but the Efimov effect is not present. In the limit of large , we show that the final particles follow a Maxwell-Boltzmann distribution if they are bosons, and a semicircle-like law if they are fermions. We argue that metastable He droplets exist with the lifetime varying over many orders of magnitudes ranging from a fraction of a nanosecond to values greatly exceeding the age of the Universe.

    nucl-thcond-mat.quant-gashep-phmath-ph+1PRA(2022)·10 citations
  2. 02

    Higher-order transverse momentum fluctuations in heavy-ion collisions

    Somadutta Bhatta🇺🇸 · Chunjian Zhang🇺🇸 · Jiangyong Jia🇺🇸

    In relativistic heavy-ion collisions, the event-by-event mean transverse momentum fluctuations are sensitive to overlap area and energy density fluctuations in initial state. We present a framework to calculate fluctuations up to -order using standard and subevent methods, which is validated using the HIJING model. We observe a power-law dependence for cumulants of all orders as a function of charged particle multiplicity , consistent with a simple independent source picture. The fluctuation in collisions is observed to be larger than for Pb, Pb+Pb and Xe+Xe collisions at the same due to bias in number of contributing sources. The short-range correlations are greatly suppressed in subevent method in comparison to calculations based on the standard method. This study provides a baseline for transverse momentum fluctuations without the presence of final state effects.

    nucl-thhep-phnucl-exPRC(2022)·24 citations
  3. 03

    Density dependence of the nuclear symmetry energy and neutron skin thickness in the KIDS framework

    Panagiota Papakonstantinou

    The KIDS framework for the nuclear equation of state (EoS) and energy density functional (EDF) offers the possibility to explore systematically the effect of EoS parameters on predictions for a variety of observables. The EoS parameters can be varied independently of each other and independently of assumptions regarding the in-medium nucleon effective mass. Here I present a pilot study of the neutron skin thickness (NST) in nuclei of current interest. The results indicate that variations of the symmetry energy slope parameter L by roughly 10 MeV and variations of the droplet-model counterpart of the curvature parameter by roughly 20 MeV affect predictions by comparable amounts. However, structural details may also have sizable effects on predictions, notably in the cases of Ni and Pb. This work is part of a systematic investigation of the NST within the KIDS framework and of a broader effort to constrain the density dependence of the nuclear symmetry energy.

    nucl-thnucl-exAdv.Nucl.Phys.(2022)·2 citations
  4. 04

    Systematic study for the surface properties of neutron star

    Ankit Kumar · H. C. Das · Jeet Amrit Pattnaik · S. K. Patra

    [Background] In our earlier work {\bf [Phys. Rev. C 104, 055804 (2021)]}, we studied the surface properties of a neutron star, assuming it as a huge finite nucleus containing protons, neutrons, electrons, and muons. For the first time, we reported these results of a neutron star for a few representative masses. In the present paper, we give a detailed study of these quantities to draw definite conclusions. [Method]To carry forward our earlier idea, the energy density functional of the momentum space of neutron star matter is converted to the coordinate space in a local density approximation. This functional is again used to derive the neutron star surface properties within the coherent density fluctuation model using the weight function obtained from the density profile of the neutron star using the recently developed G3 and widely used NL3 and IU-FSU parameter sets in the context of relativistic mean-field formalism. [Results] The systematic surface properties of the neutron star, such as incompressibility, symmetry energy, slope parameter, and curvature coefficient, is calculated. The volume and surface components of the total symmetry energy are decomposed with the help of the factor obtained from the volume to surface ratio of the symmetry energies in the liquid drop limit of Danielewicz. The magnitude of the computed surface quantities increases with the neutron star's mass. [Conclusion] The incompressibility , symmetry energy , slope parameter and curvature coefficient of the neutron stars with different mass are analyzed and found to be model dependent. NL3 is the stiffest equation of state endue us with the higher magnitude of surface quantities as compared to the G3 and IU-FSU forces.

    nucl-thastro-ph.HEPRC(2022)·1 citation
  5. 05

    Collision centrality and system size dependences of light nuclei production via dynamical coalescence mechanism

    Yi-Lin Cheng · Song Zhang · Yu-Gang Ma

    Light (anti-)nuclei in relativistic heavy-ion collisions are considered to be formed by the coalescence mechanism of (anti-)nucleons in the present work. Using a dynamical phase-space coalescence model coupled with a multi-phase transport (AMPT) model, we explore the formation of light clusters such as deuteron, triton and their anti-particles in different centralities for Au + Au collisions at GeV. The calculated transverse momentum spectra of protons, deuterons, and tritons are comparable to those of experimental data from the RHIC-STAR collaboration. Both coalescence parameters for (anti-)deuteron and for triton increase with the transverse momentum as well as the collision centrality, and they are comparable with the measured values in experiments. The effect of system size on the production of light nuclei is also investigated by B + B, O + O, Ca + Ca, and Au + Au systems in central collisions. The results show that yields of light nuclei increase with system size, while the values of coalescence parameters present an opposite trend. It is interesting to see that the system size, as well as the centrality dependence of ( = 2, 3), falls into the same group, which further demonstrates production probability of light nuclei is proportional to the size of the fireball. Furthermore, we compare our coalescence results with other models, such as the thermal model and analytic coalescence model, it seems that the description of light nuclei production is consistent with each other.

    nucl-thnucl-exEPJA(2021)·11 citations
  6. 06

    Local variations of charge radii for nuclei with even from 84 to 120

    Rong An · Xiao-Xu Dong · Li-Gang Cao · Feng-Shou Zhang

    Pronounced changes of nuclear charge radii provide a stringent benchmark on the theoretical models and play a vital role in recognizing various nuclear phenomena. In this work, the systematic evolutions of nuclear charge radii along even =84-120 isotopic chains are firstly investigated by the recently developed new ansatz under the covariant density functional. The calculated results show that the shell closure effects of nuclear charge radii are remarkably shown at the neutron numbers and 184. Interestingly, the arch-like shapes of charge radii between these two strong neutron closed shells are naturally observed. Across the shell closure, the abrupt increase in charge radii is still evidently emerged. In addition, the rapid raise of nuclear charge radii from the neutron numbers to is also disclosed clearly in superheavy regions due to the enhanced shape deformation.

    nucl-thCommun.Theor.Phys.(2023)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE