Nucleon momentum distributions in asymmetric nuclear matter

Yang, Zu-Xing; Shang, Xiuling; Yong, Gao‐Chan; Zuo, Wei; Gao, Yuan

doi:10.1103/physrevc.100.054325

Cited by 16 publications

(17 citation statements)

References 70 publications

(89 reference statements)

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“…The divergence of (50) for n b → 0 will disappear only for constant X d = 1. The relative importance of the terms proportional to k −1 nuc strongly reduces with increasing density, so that a rise driven by the σ meson contribution is observed at larger n b values, until a maximum is reached.…”

Section: Mass Shift Derivativesmentioning

confidence: 96%

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Embedding short-range correlations in relativistic density functionals through quasi-deuterons

Burrello,

Typel

2022

Preprint

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Background: The formation of clusters at sub-saturation densities, as a result of many-body correlations, constitutes an essential feature for a reliable modelization of the nuclear matter equation of state (EoS). Phenomenological models that make use of energy density functionals (EDFs) offer a convenient approach to account for the presence of these bound states of nucleons when introduced as additional degrees of freedom. However, in these models clusters dissolve, by construction, when the nuclear saturation density is approached from below, revealing inconsistencies with recent findings that evidence the existence of short-range correlations (SRCs) even at larger densities.Purpose: The idea of this work is to incorporate SRCs in established models for the EoS, in light of the importance of these features for the description of heavy-ion collisions, nuclear structure and in the astrophysical context. Our aim is to describe SRCs at supra-saturation densities by using effective quasi-clusters immersed in dense matter as a surrogate for correlations, in a regime where cluster dissolution is usually predicted in phenomenological models.Method: Within the EDF framework, we explore a novel approach to embed SRCs within a relativistic meanfield model with density dependent couplings through the introduction of suitable in-medium modifications of the cluster properties, in particular their binding energy shifts, which are responsible for describing the cluster dissolution. As a first exploratory step, the example of a quasi-deuteron within the generalized relativistic density functional approach is investigated. The zero temperature case is examined, where the deuteron fraction is given by the density of a boson condensate.Results: For the first time, suitable parameterizations of the cluster mass shift at zero temperature are derived for all baryon densities. They are constrained by experimental results for the effective deuteron fraction in nuclear matter near saturation and by microscopic many-body calculations in the low-density limit. A proper description of well-constrained nuclear matter quantities at saturation is kept through a refit of the nucleon meson coupling strengths. The proposed parameterizations allow to also determine the density dependence of the quasi-deuteron mass fraction at arbitrary isospin asymmetries. The strength of the deuteron-meson couplings is assessed to be of crucial importance. Novel effects on some thermodynamic quantities, such as the matter incompressibility, the symmetry energy and its slope, are finally discerned and discussed. Conclusions:The findings of the present study represent a first step to improve the description of nuclear matter and its EoS at supra-saturation densities in EDFs by considering correlations in an effective way. In a next step, the single-particle momentum distributions in nuclear matter can be explored using proper wave functions of the quasi-deuteron in the medium. The momentum distributions is expected to exhibit a high-momentum tail, as observed in ...

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Section: Mass Shift Derivativesmentioning

confidence: 96%

“…The condensation condition allows to calculate, for a given mass-fraction function, the quasi-deuteron mass shift and its derivatives at high-densities through Eqs. (44), (47) and (50), respectively. However, the density dependence of the mass fraction X d is not known a priori, in particular at supra-saturation densities.…”

Section: Mass Shift Parameterizationmentioning

confidence: 99%

Embedding short-range correlations in relativistic density functionals through quasi-deuterons

Burrello,

Typel

2022

Preprint

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“…In the past decade the the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model (IBUU) have been very successful in describing the dynamical evolution of nucleons in phase space, as well as the reaction dynamics of heavy-ion collisions [29][30][31][32]. The present IBUU transport model originating from the IBUU04 model can describe the time evolution of the single-particle phase-space distribution function,…”

Section: The Theoretical Modelmentioning

confidence: 99%

Pion production and absorption in heavy-ion collisions

Gao,

Zhang,

Yong

et al. 2020

Preprint

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Based on the isospin dependent transport model IBUU, the pion production and its absorption are thoroughly studied in the central collision of Au + Au at a beam energy of 400 MeV/nucleon. It is found that the pions are firstly produced by the hard ∆ decay at the average density around 1.75ρ0, whereas about 18% of them are absorbed absolutely in the subsequent inelastic collisions. For the free pions observed, more than half of them have been scattered for one or more times before they are free from matter. And the more scattering numbers of pions, the higher the momentum they possess. These pions, due to longer time of their existence in high density nuclear matter, carry more information about the symmetry energy of the nuclear matter at high densities.

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“…Since the discovery of the atomic nucleus [1], density information has played a crucial role in the study of nuclear structure, especially in explaining the nature of nuclear force and the fundamental properties of nuclear matter [2]. For example, in studies of high-momentum tails(HMT) induced by short-range correlations(SRC), it has been found that the percentage of tails is highly dependent on the density [3][4][5]. The asymmetry potential is density-dependent, which is influenced by the Pauli blocking of the ∆-decay and the thickness of the neutron skin [6].…”

Section: Introductionmentioning

confidence: 99%

Taming nucleon density distributions with deep neural network method

Yang,

Zuo,

Yin

et al. 2020

Preprint

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We investigate the density distributions of finite nuclei employing a well-designed deep neural network method. We calculate the target nucleon density distributions with Skyrme density functional theories, which are used to train the networks. We find that the training with only about 10% nuclei (300 − 400) is sufficient to describe the nucleon density distributions of all the nuclear chart within 2% relative error. The relative error comes to 5% when about 200 proton(neutron) density distributions are used for training. We obtained very similar results for different Skyrme density functional theories. Therefore the ability to train networks is weakly dependent on the theoretical model. Moreover, in the process of machine learning, there is a turning point showing the transition from the Fermi-like distribution to the realistic Skyrme distribution, which provides significant properties of convergence process.

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Nucleon momentum distributions in asymmetric nuclear matter

Cited by 16 publications

References 70 publications

Embedding short-range correlations in relativistic density functionals through quasi-deuterons

Embedding short-range correlations in relativistic density functionals through quasi-deuterons

Pion production and absorption in heavy-ion collisions

Taming nucleon density distributions with deep neural network method

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