Nuclear Theory·nucl-th

Wednesday·January 11, 2023

9 papers—4 primary·5 cross-listed

01
Constraints on Nuclear Symmetry Energy Parameters
James M. Lattimer
A review is made of constraints on the nuclear symmetry energy parameters arising from nuclear binding energy measurements, theoretical chiral effective field predictions of neutron matter properties, the unitary gas conjecture, and measurements of neutron skin thicknesses and dipole polarizabilities. While most studies have been confined to the parameters $S_{V}$ and $L$ , the important roles played by, and constraints on $K_{sym}$ , or, equivalently, the neutron matter incompressibility $K_{N}$ , are discussed. Strong correlations among $S_{V}, L$ , and $K_{N}$ are found from both nuclear binding energies and neutron matter theory. However, these correlations somewhat differ in the two cases, and those from neutron matter theory have smaller uncertainties. To 68\% confidence, it is found from neutron matter theory that $S_{V} = 32.0 \pm 1.1$ MeV, $L = 51.9 \pm 7.9$ MeV and $K_{N} = 152.2 \pm 38.1$ MeV. Theoretical predictions for neutron skin thickness and dipole polarizability measurements of the neutron-rich nuclei $^{48}$ Ca, $^{120}$ Sn, and $^{208}$ Pb are compared to recent experimental measurements, most notably the CREX and PREX neutron skin experiments from Jefferson Laboratory. By themselves, PREX I+II measurements of $^{208}$ Pb and CREX measurement of $^{48}$ Ca suggest $L = 121 \pm 47$ MeV and $L = - 5 \pm 40$ MeV, respectively, to 68\% confidence. However, we show that nuclear interactions optimally satisfying both measurements imply $L = 53 \pm 13$ MeV, nearly the range suggested by either nuclear mass measurements or neutron matter theory, and is also consistent with nuclear dipole polarizability measurements. This small parameter range implies $R_{1.4} = 11.6 \pm 1.0$ km and $Λ_{1.4} = 22 8_{- 90}^{+ 148}$ , which are consistent with NICER X-ray and LIGO/Virgo gravitational wave observations of neutron stars.
nucl-thastro-ph.SRParticles(2023)·142 citations
02
Fourier coefficients of noninterdependent collective motions in heavy-ion collisions
Zhiwan Xu🇺🇸 · Gang Wang🇺🇸 · Aihong Tang🇺🇸 · Huan Zhong Huang🇺🇸
We present a scenario in heavy-ion collisions where different modes of collective motions are noninterdependent, driven by factorized actions in the created nuclear medium. Such physics mechanisms could each dominate at a distinct evolution stage, or coexist simultaneously. If the probability of particle emission is modulated by each nondependent collective motion with a single-harmonic Fourier expansion, the particle azimuthal distribution should be the product of all these expansions. Consequently, nonleading cross terms between collectivity modes appear, and their contributions to experimental observables could be significant. In particular, we argue that the chiral magnetic effect (CME) and elliptic flow can develop separately, with their convolution affecting the observable that is sensitive to the shear-induced CME. We will use the event-by-event anomalous-viscous fluid dynamics model to illustrate the effects of this scenario. Besides giving insights into searches for the CME, we also propose feasible experimental tests based on conventional flow harmonics, and demonstrate the emergence of nonleading cross terms with a multiphase transport model.
nucl-thnucl-exPRC(2023)·5 citations
03
Examination of nucleon distribution with Bayesian imaging for isobar collisions
Yi-Lin Cheng🇩🇪 · Shuzhe Shi🇨🇳 · Yu-Gang Ma🇨🇳 · Horst Stöcker🇩🇪 · Kai Zhou🇩🇪
Relativistic collision of isobaric systems is found to be valuable in differentiating the nucleon distributions for nuclei with the same mass number. In recent contrast experiment of $_{44}^{96} Ru +_{44}^{96} Ru$ versus $_{40}^{96} Zr +_{40}^{96} Zr$ collisions at $s_{NN} = 200 GeV$ , the ratios of multiplicity distribution, elliptic flow, triangular flow, and radial flow are precisely measured and found to be significantly different from unity, indicating the difference in the shapes of the isobar pair. In this work, we investigate the feasibility of nuclear structure reconstruction from heavy-ion collision observables. We perform Bayesian Inference with employing the Monte-Carlo Glauber model as an estimator of the mapping from nuclear structure to the final state observables and to provide the mock data for reconstruction. By varying combination of observables included in the mock data, we find it plausible to infer Woods--Saxon parameters from the observables. We also observe that single-system multiplicity distribution for the isobar system, rather than their ratio, is crucial to simultaneously determine the nuclear structure for the isobar system.
nucl-thhep-exhep-phnucl-exPRC(2023)·20 citations
04
$Λ N N$ content of $Λ$ -nucleus potential
Eliahu Friedman🇮🇱 · Avraham Gal🇮🇱
A minimally constructed $Λ$ -nucleus density-dependent optical potential is used to calculate binding energies of observed $1 s_{Λ}$ , $1 p_{Λ}$ states across the periodic table, leading to a repulsive $Λ N N$ contribution $D_{Λ}^{(3)} \approx 14$ MeV to the phenomenological $Λ$ -nucleus potential depth $D_{Λ} \approx - 30$ MeV. This value is significant in connection with the so-called 'hyperon puzzle'.
nucl-thhep-phnucl-exEPJ Web Conf.(2022)·5 citations
05
1+1D Hadrons Minimize their Biparton Renyi Free Energy
Pouya Asadi🇺🇸 · Varun Vaidya🇺🇸
We use a variational method to calculate the spectrum and the parton distribution function of ground state hadrons of various gauge theories in 1+1 dimensions. The template functions in our method minimize a free energy functional defined as a combination of free valence partons' kinetic energy on the lightcone and the Renyi entanglement entropy of biparton subsystems. Our results show that hadrons in these theories minimize the proposed free energy. The success of this technique motivates applying it to confining gauge theories in higher dimensions.
↳ hep-thhep-phnucl-thquant-phPRD(2023)·15 citations
06
Multiple Mechanisms in Proton-Induced Nucleon Removal at $\sim$ 100 MeV/Nucleon
T. Pohl🇩🇪 · Y. L. Sun🇩🇪 · A. Obertelli🇩🇪 · J. Lee🇨🇳 · M. Gomez-Ramos🇪🇸 · K. Ogata🇯🇵 · K. Yoshida🇯🇵 · B.S. Cai🇨🇳 · C.X. Yuan🇨🇳 · B. A. Brown🇺🇸 · H. Baba🇯🇵 · D. Beaumel🇫🇷 and 39 other authors
We report on the first proton-induced single proton- and neutron-removal reactions from the neutron-deficient $^{14}$ O nucleus with large Fermi-surface asymmetry $S_{n} - S_{p}$ = 18.6 MeV at $\sim$ 100 MeV/nucleon, a widely used energy regime for rare-isotope studies. The measured inclusive cross sections and parallel momentum distributions of the $^{13}$ N and $^{13}$ O residues are compared to the state-of-the-art reaction models, with nuclear structure inputs from many-body shell-model calculations. Our results provide the first quantitative contributions of multiple reaction mechanisms including the quasifree knockout, inelastic scattering and nucleon transfer processes. It is shown that the inelastic scattering and nucleon transfer, usually neglected at such energy regime, contribute about 50% and 30% to the loosely bound proton and deeply bound neutron removal, respectively. These multiple reaction mechanisms should be considered in analyses of inclusive one-nucleon removal cross sections measured at intermediate energies for quantitative investigation of single-particle strengths and correlations in atomic nuclei.
↳ nucl-exnucl-thPRL(2023)·17 citations
07
Generational variance reduction in Monte Carlo criticality simulations as a way of mitigating unwanted correlations
Kévin Fröhlicher · Eric Dumonteil · Loïc Thulliez · Julien Taforeau · Mariya Brovchenko
Monte Carlo criticality simulations are widely used in nuclear safety demonstrations, as they offer an arbitrarily precise estimation of global and local tallies while making very few assumptions. However, since the inception of such numerical approaches, it is well known that bias might affect both the estimation of errors on these tallies and the tallies themselves. In particular, stochastic modeling approaches developed in the past decade have shed light on the prominent role played by spatial correlations through a phenomenon called neutron clustering. This effect is particularly of great significance when simulating loosely coupled systems (i.e., with a high dominance ratio). In order to tackle this problem, this paper proposes to recast the power iteration technique of Monte Carlo criticality codes into a variance reduction technique called Adaptative Multilevel Splitting. The central idea is that iterating over neutron generations can be seen as pushing a sub-population of neutrons towards a generational detector (instead of a spatial detector as variance reduction techniques usually do). While both approaches allow for neutron population control, the former blindly removes or splits neutrons. In contrast, the latter optimizes spatial, generational, and spectral attributes of neutrons when they are removed or split through an adjoint flux estimation, hence tempering both generational and spatial correlations. This is illustrated in the present article with a simple case of a bare slab reactor in the one speed theory on which the Adaptive Multilevel Splitting was applied and compared to variations of the Monte Carlo power iteration method used in neutron transport. Besides looking at the resulting efficiency of the methods, this work also aims at highlighting the main mechanisms of the Adaptive Multilevel Splitting in criticality calculations.
↳ cond-mat.stat-mechnucl-thphysics.comp-phNucl.Sci.Eng.(2024)·0 citations
08
Nuclear $β$ decay as a probe for physics beyond the Standard Model
M. Brodeur🇺🇸 · N. Buzinsky🇺🇸 · M. A. Caprio🇺🇸 · V. Cirigliano🇺🇸 · J. A. Clark🇺🇸 · P. J. Fasano🇺🇸 · J. A. Formaggio🇺🇸 · A. T. Gallant🇺🇸 · A. Garcia🇺🇸 · S. Gandolfi🇺🇸 · S. Gardner🇺🇸 · A. Glick-Magid🇺🇸 and 34 other authors
This white paper was submitted to the 2022 Fundamental Symmetries, Neutrons, and Neutrinos (FSNN) Town Hall Meeting in preparation for the next NSAC Long Range Plan. We advocate to support current and future theoretical and experimental searches for physics beyond the Standard Model using nuclear $β$ decay.
↳ nucl-exnucl-th26 citations
09
Role of chemical potential at kinetic freeze-out using Tsallis non-extensive statistics in proton-proton collisions at the Large Hadron Collider
Girija Sankar Pradhan🇮🇳 · Dushmanta Sahu🇮🇳 · Rutuparna Rath🇮🇹 · Raghunath Sahoo🇮🇳 · Jean Cleymans🇿🇦
The charged-particle transverse momentum spectra ( $p_{T}$ -spectra) measured by the ALICE collaboration for $pp$ collisions at $s =$ 7 and 13 TeV have been studied using a thermodynamically consistent form of Tsallis non-extensive statistics. The Tsallis distribution function is fitted to the $p_{T}$ -spectra and the results are analyzed as a function of final state charged-particle multiplicity for various light flavor and strange particles, such as $π^{\pm}, K^{\pm}, p + p ˉ, ϕ, Λ + Λ ˉ, Ξ + Ξ ˉ, Ω + Ω ˉ$ . At the LHC energies, particles and antiparticles are produced in equal numbers. However, the equality of particle and antiparticle yields at the kinetic freeze-out may imply that they have the same but opposite chemical potential which is not necessarily zero. We use an alternative procedure that makes use of parameter redundancy, by introducing a finite chemical potential at the kinetic freeze-out stage. This article emphasizes the importance of the chemical potential of the system produced in $pp$ collisions at the LHC energies using the Tsallis distribution function which brings the system to a single freeze-out scenario.
↳ hep-phhep-exnucl-exnucl-thEPJA(2024)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE