Nuclear Theory·nucl-th

Tuesday·August 10, 2021

15 papers—8 primary·7 cross-listed

01
Beta equilibrium under neutron star merger conditions
Mark G. Alford🇺🇸 · Alexander Haber🇺🇸 · Steven P. Harris🇺🇸 · Ziyuan Zhang🇺🇸
We calculate the nonzero-temperature correction to the beta equilibrium condition in nuclear matter under neutron star merger conditions, in the temperature range $1$ MeV $< T ≲ 5$ MeV. We improve on previous work by using a consistent description of nuclear matter based on the IUF and SFHo relativistic mean field models. This includes using relativistic dispersion relations for the nucleons, which we show is essential in these models. We find that the nonzero-temperature correction can be of order $10$ to $20$ MeV, and plays an important role in the correct calculation of Urca rates, which can be wrong by factors of $10$ or more if it is neglected.
nucl-thastro-ph.HEUniverse(2021)·60 citations
02
Bayesian approach to long-range correlations and multiplicity fluctuations in nucleus-nucleus collisions
Kianusch Vahid Yousefnia🇫🇷 · Atharva Kotibhaskar🇮🇳 · Rajeev Bhalerao🇮🇳 · Jean-Yves Ollitrault🇫🇷
The number of particles detected in a nucleus-nucleus collision strongly depends on the impact parameter of the collision. Therefore, multiplicity fluctuations, as well as rapidity correlations of multiplicities, are dominated by impact parameter fluctuations. We present a method based on Bayesian inference which allows for a robust reconstruction of fluctuations and correlations at fixed impact parameter. We apply the method to ATLAS data on the distribution of charged multiplicity and transverse energy. We argue that multiplicity fluctuations are smaller at large rapidity than around central rapidity. We suggest simple, new analyses, in order to confirm this effect.
nucl-thhep-phnucl-exPRC(2022)·19 citations
03
Singularities and Accumulation of Singularities of $π$ N Scattering amplitudes
Qu-Zhi Li🇨🇳 · Han-Qing Zheng🇨🇳
It is demonstrated that for the isospin $I = 1/2$ $π$ N scattering amplitude, $T^{I = 1/2} (s, t)$ , $s = (m_{N}^{2} - m_{π}^{2})^{2} / m_{N}^{2}$ and $s = m_{N}^{2} + 2 m_{π}^{2}$ are two accumulation points of poles on the second sheet of complex $s$ plane, and are hence accumulation of singularities of $T^{I = 1/2} (s, t)$ . For $T^{I = 3/2} (s, t)$ , $s = (m_{N}^{2} - m_{π}^{2})^{2} / m_{N}^{2}$ is the accumulation point of poles on the second sheet of complex $s$ plane. The proof is valid up to all orders of chiral expansions.
nucl-thhep-thmath-phmath.MPCommun.Theor.Phys.(2022)·9 citations
04
Fragment Intrinsic Spins and Fragments' Relative Orbital Angular Momentum in Nuclear Fission
Aurel Bulgac · Ibrahim Abdurrahman · Kyle Godbey · Ionel Stetcu
We present the first fully unrestricted microscopic calculations of the primary fission fragment intrinsic spins and of the fission fragments' relative orbital angular momentum for $^{236}$ U $^{*}$ , $^{240}$ Pu $^{*}$ , and $^{252}$ Cf using the time-dependent density functional theory framework. Within this microscopic approach, free of restrictions and unchecked assumptions and which incorporates the relevant physical observables for describing fission, we evaluate the triple distribution of the fission fragment intrinsic spins and of their fission fragments' relative orbital angular momentum and show that their dynamics is dominated by their bending collective modes, in contradistinction to the predictions of the existing phenomenological models and some interpretations of experimental data.
nucl-thPRL(2022)·61 citations
05
A brief account of Steven Weinberg's legacy in ab initio many-body theory
Christian Drischler🇺🇸 · Scott K. Bogner🇺🇸
In this contribution to the special issue "Celebrating 30 years of Steven Weinberg's papers on Nuclear Forces from Chiral Lagrangians," we emphasize the important role chiral effective field theory has played in leading nuclear physics into a precision era. To this end, we share our perspective on a few of the recent advances made in ab initio calculations of nuclear structure and nuclear matter observables, as well as Bayesian uncertainty quantification of effective field theory truncation errors.
nucl-thhep-phnucl-exFew Body Syst.(2021)·9 citations
06
Systematic study of two-proton radioactivity with a screened electrostatic barrier
Y. T. Zou · X. Pan · X. H. Li · H. M. Liu · X. J. Wu · B. He
In this study, a phenomenological model is proposed based on Wentzel-Kramers-Brillouin (WKB) theory and applied to investigate the two-proton ( $2 p$ ) radioactive half-lives of nuclei near or beyond the proton drip line. The total diproton-daughter nucleus interaction potential is composed of the Hulthen-type electrostatic term and the centrifugal term. The calculated $2 p$ radioactive half-lives can accurately reproduce the existing 10 experimental datasets of five true $2 p$ radioactive nuclei with $σ$ = 0.736. In addition, we extend this model to predict the half-lives of possible $2 p$ radioactive nuclei whose $2 p$ radioactivity is energetically allowed or observed but not yet quantified in NUBASE2016. The predicted results are in agreement with those obtained using the Gamow-like model, generalized liquid drop model, Sreeja formula, and Liu formula.
nucl-thCPC(2021)·11 citations
07
Learning Langevin dynamics with QCD phase transition
Lingxiao Wang🇩🇪 · Lijia Jiang🇩🇪 · Kai Zhou🇩🇪
In this proceeding, the deep Convolutional Neural Networks (CNNs) are deployed to recognize the order of QCD phase transition and predict the dynamical parameters in Langevin processes. To overcome the intrinsic randomness existed in a stochastic process, we treat the final spectra as image-type inputs which preserve sufficient spatiotemporal correlations. As a practical example, we demonstrate this paradigm for the scalar condensation in QCD matter near the critical point, in which the order parameter of chiral phase transition can be characterized in a $1 + 1$ -dimensional Langevin equation for $σ$ field. The well-trained CNNs accurately classify the first-order phase transition and crossover from $σ$ field configurations with fluctuations, in which the noise does not impair the performance of the recognition. In reconstructing the dynamics, we demonstrate it is robust to extract the damping coefficients $η$ from the intricate field configurations.
nucl-thnucl-exphysics.data-anEPJ Web Conf.(2022)·2 citations
08
Global hyperon polarization and effects of decay feeddown
Hui Li🇨🇳 · Xiao-Liang Xia🇨🇳 · Xu-Guang Huang🇨🇳 · Huan Zhong Huang🇨🇳
We study the global polarizations of $Λ$ , $Ξ^{-}$ , and $Ω^{-}$ hyperons in noncentral Au+Au collisions at $s_{NN} =$ 7.7-200 GeV. We highlight the importance of effect of decay feeddown to the measured global polarization. With the decay contributions taken into account, the global polarization ordering $P_{Ω^{-}} > P_{Ξ^{-}} > P_{Λ}$ can be naturally explained, which is consistent with the observation recently reported from the STAR experiment from Au+Au collisions at 200 GeV. We also extend our calculations to predict expectations from the RHIC-BES II data.
nucl-thEPJ Web Conf.(2022)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE