Nuclear Theory·nucl-th

Wednesday·February 21, 2024

7 papers—5 primary·2 cross-listed

01
Intruder band mixing in an ab initio description of 12Be
Anna E. McCoy · Mark A. Caprio · Pieter Maris · Patrick J. Fasano
The spectrum of 12Be exhibits exotic features, e.g., an intruder ground state and shape coexistence, normally associated with the breakdown of a shell closure. While previous phenomenological treatments indicated the ground state has substantial contributions from intruder configurations, it is only with advances in computational abilities and improved interactions that this intruder mixing is observed in ab initio no-core shell model (NCSM) predictions. In this work, we extract electromagnetic observables and symmetry decompositions from the NCSM wave functions to demonstrate that the low-lying positive parity spectrum can be explained in terms of mixing of rotational bands with very different intrinsic structure coexisting within the low-lying spectrum. These observed bands exhibit an approximate SU(3) symmetry and are qualitatively consistent with Elliott model predictions.
nucl-thPLB(2024)·16 citations
02
The influence of hadronic rescatterings on the net-baryon number fluctuations
Qian Chen · Rui Wen · Shi Yin · Wei-jie Fu · Zi-Wei Lin · Guo-Liang Ma
Fluctuations of conserved charges, such as the net-baryon number fluctuations, are influenced by different dynamical evolution processes. In this paper, we investigate the influence of hadronic rescatterings on different orders of cumulants of the net-baryon number distribution. At the start of hadronic rescatterings, we introduce net-baryon number distributions reconstructed based on net-baryon cumulants of different orders obtained from computation in functional renormalization group (FRG), where the distributions were constructed using the maximum entropy method. This way we introduce the critical fluctuations of Quantum Chromodynamics (QCD) into the AMPT model. Firstly, we find that hadronic rescatterings have distinct effects on cumulant ratios of different orders for the net-baryon number. Secondly, we observe that the effect of hadronic rescatterings is more significant for critical fluctuations than dynamical fluctuations, because the two-, three- and four-particle correlation functions due to critical fluctuations are weakened more significantly by hadronic rescatterings.
nucl-thhep-phnucl-ex5 citations
03
Effects of incompressibility $K_{0}$ in heavy-ion collisions at intermediate energies
Xiao-Xiao Long🇨🇳 · Gao-Feng Wei🇨🇳
Within the possible least uncertainty on the nuclear incompressibility $K_{0}$ , we examine effects of $K_{0}$ in heavy-ion collisions at intermediate energies. Based on simulations of Au + Au collision at 400 MeV/nucleon using an isospin- and momentum-dependent transport model, we find that the incompressibility $K_{0}$ indeed affects significantly the attainable density in central regions, and thus the particle productions and/or distributions at final states, e.g., nucleon rapidity distributions and yields of charged pions. Nevertheless, through examining the free neutron over proton ratios $n / p$ , the neutron-proton differential transverse and directed flows as well as the charged pion ratio $π^{-} / π^{+}$ and its kinetic energy distribution, we find that these observables are less affected by the uncertainty of $K_{0}$ , but mainly sensitive to the slope of symmetry energy at the saturation density. We also compare and discuss our results with the corresponding data.
nucl-thnucl-exPRC(2024)·9 citations
04
Causal and Stable Relativistic Hydrodynamic Fluctuations
Nicki Mullins · Mauricio Hippert · Jorge Noronha · Lorenzo Gavassino
When two nuclei collide close to the speed of light, a fluid state known as the quark-gluon plasma is formed. Attempts to understand the dynamics of this fluid have generated significant research into dissipative relativistic fluid dynamics. The fluctuation-dissipation theorem implies that any dissipative dynamical system will also experience thermal fluctuations; however, such fluctuations are not typically included in the modeling of the quark-gluon plasma. This work discusses a new method of determining whether a hydrodynamic framework is consistent with thermal fluctuations. We develop a new method for calculating the noise correlator of relativistic hydrodynamic systems and apply it to Israel-Stewart theory in a general hydrodynamic frame.
nucl-thhep-ph0 citations
05
Assessing Correlated Truncation Errors in Modern Nucleon-Nucleon Potentials
P. J. Millican🇺🇸 · R. J. Furnstahl🇺🇸 · J. A. Melendez🇺🇸 · D. R. Phillips🇸🇪 · M. T. Pratola🇺🇸
We test the BUQEYE model of correlated effective field theory (EFT) truncation errors on Reinert, Krebs, and Epelbaum's semi-local momentum-space implementation of the chiral EFT ( $χ$ EFT) expansion of the nucleon-nucleon (NN) potential. This Bayesian model hypothesizes that dimensionless coefficient functions extracted from the order-by-order corrections to NN observables can be treated as draws from a Gaussian process (GP). We combine a variety of graphical and statistical diagnostics to assess when predicted observables have a $χ$ EFT convergence pattern consistent with the hypothesized GP statistical model. Our conclusions are: First, the BUQEYE model is generally applicable to the potential investigated here, which enables statistically principled estimates of the impact of higher EFT orders on observables. Second, parameters defining the extracted coefficients such as the expansion parameter $Q$ must be well chosen for the coefficients to exhibit a regular convergence pattern -- a property we exploit to obtain posterior distributions for such quantities. Third, the assumption of GP stationarity across lab energy and scattering angle is not generally met; this necessitates adjustments in future work. We provide a workflow and interpretive guide for our analysis framework, and show what can be inferred about probability distributions for $Q$ , the EFT breakdown scale $Λ_{b}$ , the scale associated with soft physics in the $χ$ EFT potential $m_{eff}$ , and the GP hyperparameters. All our results can be reproduced using a publicly available Jupyter notebook, which can be straightforwardly modified to analyze other $χ$ EFT NN potentials.
nucl-thhep-phphysics.data-anPRC(2024)·15 citations
06
Lüscher equation with long-range forces
Rishabh Bubna🇩🇪 · Hans-Werner Hammer🇩🇪 · Fabian Müller🇩🇪 · Jin-Yi Pang🇨🇳 · Akaki Rusetsky🇩🇪 · Jia-Jun Wu🇨🇳
We derive the modified Lüscher equation in the presence of the long-range force caused by the exchange of a light particle. It is shown that the use of this equation enables one to circumvent the problems related to the strong partial-wave mixing and the t-channel sub-threshold singularities. It is also demonstrated that the present method is intrinsically linked to the so-called modified effective-range expansion (MERE) in the infinite volume. A detailed comparison with the two recently proposed alternative approaches is provided.
↳ hep-lathep-phnucl-thJHEP(2024)·43 citations
07
Go Green: Selected Configuration Interaction as a More Sustainable Alternative for High Accuracy
Pierre-François Loos · Yann Damour · Abdallah Ammar · Michel Caffarel · Fábris Kossoski · Anthony Scemama
Recently, a new distributed implementation of the full configuration interaction (FCI) method has been reported [Gao et al. J. Chem Theory Comput. 2024, 20, 1185]. Thanks to a hybrid parallelization scheme, the authors were able to compute the exact energy of propane (\ce{C3H8}) in the minimal basis STO-3G. This formidable task involves handling an active space of 26 electrons in 23 orbitals or a Hilbert space of \SI{1.3d12} determinants. This is, by far, the largest FCI calculation reported to date. Here, we illustrate how, from a general point of view, selected configuration interaction (SCI) can achieve microhartree accuracy at a fraction of the computational and memory cost, via a sparse exploration of the FCI space. The present SCI calculations are performed with the \textit{Configuration Interaction using a Perturbative Selection made Iteratively} (CIPSI) algorithm, as implemented in a determinant-driven way in the \textsc{quantum package} software. The present study reinforces the common wisdom that among the exponentially large number of determinants in the FCI space, only a tiny fraction of them significantly contribute to the energy. More importantly, it demonstrates the feasibility of achieving comparable accuracy using more reasonable and sustainable computational resources, hence reducing the ever-growing carbon footprint of computational chemistry.
↳ physics.chem-phcond-mat.mtrl-scicond-mat.str-elnucl-th+12 citations

Affiliations

first authorsco-authorsvia INSPIRE

Intruder band mixing in an ab initio description of 12Be

The influence of hadronic rescatterings on the net-baryon number fluctuations

Effects of incompressibility K0​ in heavy-ion collisions at intermediate energies

Causal and Stable Relativistic Hydrodynamic Fluctuations

Assessing Correlated Truncation Errors in Modern Nucleon-Nucleon Potentials

Lüscher equation with long-range forces

Go Green: Selected Configuration Interaction as a More Sustainable Alternative for High Accuracy

Affiliations

Effects of incompressibility $K_{0}$ in heavy-ion collisions at intermediate energies