Nuclear Theory·nucl-th

Monday·June 21, 2021

6 papers—4 primary·2 cross-listed

01
Statistical Multifragmentation Model Within the Extended Morphological Thermodynamics Approach
V. S. Kucherenko · K. A. Bugaev · V. Sagun · O. Ivanytskyi
On the basis of morphological thermodynamics we develop an exactly solvable version of statistical mutifragmentation model for the nuclear liquid-gas phase transition. It is shown that the hard-core repulsion between spherical nuclei generates only the bulk (volume), surface and curvature parts of the free energy of the nucleus, while the Gaussian curvature one does not appear in the derivation. The phase diagram of nuclear liquid-gas phase transition is studied for a truncated version of the developed model.
nucl-thcond-mat.stat-mechUkr.J.Phys.(2022)·0 citations
02
Decoding the Density Dependence of the Nuclear Symmetry Energy
W. G. Lynch · M. B. Tsang
The large imbalance in the neutron and proton densities in very neutron rich systems increases the nuclear symmetry energy so that it governs many aspects of neutron stars and their mergers. Extracting the density dependence of the symmetry energy therefore constitutes an important scientific objective. Many analyses have been limited to extracting values for the symmetry energy, $S_{0}$ , and its ``derivative'', $L$ , at saturation density $ρ_{0} \approx 2.6 \times 1 0^{14} g/c m^{3}$ $\approx 0.16 nucleons/f m^{3}$ , resulting in constraints that appear contradictory. We show that most experimental observables actually probe the symmetry energy at densities far from $ρ_{0}$ , making the extracted values of $S_{0}$ or $L$ imprecise. By focusing on the densities these observables actually probe, we obtain a detailed picture of the density dependence of the symmetry energy from $0.25 ρ_{0}$ to $1.5 ρ_{0}$ . From this experimentally derived density functional, we extract $L_{01} = 53.1 \pm 6.1 M e V$ at $ρ \approx 0.10 f m^{- 3}$ , a neutron skin thickness for $^{208} P b$ of $R_{n p} =$ $0.23 \pm 0.04$ fm, a symmetry pressure at saturation density of $P_{0} = 3.2 \pm 1.2 M e V / f m^{3}$ and suggests a radius for a 1.4 solar mass neutron star of $13.1 \pm 0.6$ km.
nucl-thastro-ph.HEastro-ph.SRnucl-exPLB(2022)·81 citations
03
Study of neutrino-nucleus reactions with CRISP Program (0 < $E_{ν}$ < 3 GeV)
R. Perez🇧🇷 · A. Deppman🇧🇷 · Evandro Andrade-II🇧🇷 · A.R. Samana🇧🇷 · F.G. Velasco🇧🇷 · F. Guzmán🇨🇺
The neutrino-nucleus reactions are studied at energies from 0 to 3 GeV, using the CRISP program. To simulate these reactions, CRISP uses the Monte Carlo method through an intranuclear cascade model. Quase-elastic and baryonic resonance formation channels for the neutrino-nucleon interaction are considered. The total and differential particle emission cross-sections were obtained, obtaining a good agreement with the values reported by the MiniBooNE experiment. The influence of nuclear effects on the studied reactions, such as fermionic motion, the Pauli blocking mechanism, and the nucleonic separation energy, was shown. It was not possible to simultaneously reproduce the $ν_{μ} + D$ and $ν_{μ} +^{12} C$ reactions using the same axial mass value. For the charged current quasi-elastic channel, $M_{A} = 0.95 G e V$ for the $ν_{μ} + D$ reaction, and $M_{A} = 1.35 G e V$ for the $ν_{μ} +^{12} C$ reaction. This can be solved if one considers, in addition to the neutrino-nucleon interaction, the neutrino interaction with a pair of nucleons, just as we demonstrate in the last part of this work.
nucl-thhep-phPRD(2022)·2 citations
04
Shell model analysis of the $B (E 2, 2^{+} \to 0^{+})$ 's in the A=70 T=1 triplet
S. M. Lenzi · A. Poves · A. O. Macchiavelli
he $B (E 2, 2^{+} \to 0^{+})$ transition strengths of the T=1 isobaric triplet $^{70}$ Kr, $^{70}$ Br, $^{70}$ Se, recently measured at RIKEN/RIBF, are discussed in terms of state of the art large scale shell model calculations using the JUN45 and JUN45+LNPS plus Coulomb interactions. In this letter we argue that, depending on the effective charges used, the calculations are either in line with the experimental data within statistical uncertainties, or the anomaly happens in $^{70}$ Br, rather than $^{70}$ Kr. In the latter case, we suggest that it can be due to the presence of a hitherto undetected 1 $^{+}$ T=0 state below the yrast 2 $^{+}$ T=1 state. Our results do not support a shape change of $^{70}$ Kr with respect to the other members of the isobaric multiplet.
nucl-thnucl-exPRC(2021)·13 citations
05
Equation of State Dependence of Gravitational Waves in Core-Collapse Supernovae
Oliver Eggenberger Andersen🇸🇪 · Shuai Zha🇸🇪 · André da Silva Schneider🇸🇪 · Aurore Betranhandy🇸🇪 · Sean M. Couch🇺🇸 · Evan P. O'Connor🇸🇪
Gravitational waves (GWs) provide unobscured insight into the birthplace of neutron stars (NSs) and black holes in core-collapse supernovae (CCSNe). The nuclear equation of state (EOS) describing these dense environments is yet uncertain, and variations in its prescription affect the proto-neutron star (PNS) and the post-bounce dynamics in CCSNe simulations, subsequently impacting the GW emission. We perform axisymmetric simulations of CCSNe with Skyrme-type EOSs to study how the GW signal and PNS convection zone are impacted by two experimentally accessible EOS parameters, (1) the effective mass of nucleons, $m^{⋆}$ , which is crucial in setting the thermal dependence of the EOS, and (2) the isoscalar incompressibility modulus, $K_{sat}$ . While $K_{sat}$ shows little impact, the peak frequency of the GWs has a strong effective mass dependence due to faster contraction of the PNS for higher values of $m^{⋆}$ owing to a decreased thermal pressure. These more compact PNSs also exhibit more neutrino heating which drives earlier explosions and correlates with the GW amplitude via accretion plumes striking the PNS, exciting the oscillations. We investigate the spatial origin of the GWs and show the agreement between a frequency-radial distribution of the GW emission and a perturbation analysis. We do not rule out overshoot from below via PNS convection as another moderately strong excitation mechanism in our simulations. We also study the combined effect of effective mass and rotation. In all our simulations we find evidence for a power gap near $\sim$ 1250 Hz, we investigate its origin and report its EOS dependence.
↳ astro-ph.HEnucl-thApJ(2021)·80 citations
06
Accelerated quantum Monte Carlo with mitigated error on noisy quantum computer
Yongdan Yang🇨🇳 · Bing-Nan Lu🇨🇳 · Ying Li🇨🇳
Quantum Monte Carlo and quantum simulation are both important tools for understanding quantum many-body systems. As a classical algorithm, quantum Monte Carlo suffers from the sign problem, preventing its application to most fermion systems and real time dynamics. In this paper, we introduce a novel non-variational algorithm using quantum simulation as a subroutine to accelerate quantum Monte Carlo by easing the sign problem. The quantum subroutine can be implemented with shallow circuits and, by incorporating error mitigation, can reduce the Monte Carlo variance by several orders of magnitude even when the circuit noise is significant. As such, the proposed quantum algorithm is applicable to near-term noisy quantum hardware.
↳ quant-phnucl-thPRX Quantum(2021)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE

Statistical Multifragmentation Model Within the Extended Morphological Thermodynamics Approach

Decoding the Density Dependence of the Nuclear Symmetry Energy

Study of neutrino-nucleus reactions with CRISP Program (0 < Eν​ < 3 GeV)

Shell model analysis of the B(E2,2+→0+)'s in the A=70 T=1 triplet

Equation of State Dependence of Gravitational Waves in Core-Collapse Supernovae

Accelerated quantum Monte Carlo with mitigated error on noisy quantum computer

Affiliations

Study of neutrino-nucleus reactions with CRISP Program (0 < $E_{ν}$ < 3 GeV)

Shell model analysis of the $B (E 2, 2^{+} \to 0^{+})$ 's in the A=70 T=1 triplet