Research

11 pages, 334 KiB

Open AccessArticle

Hartree–Fock Calculations in Semi-Infinite Matter with Gogny Interactions

by Dany Davesne, Alessandro Pastore and Jesus Navarro

Universe 2023, 9(9), 398; https://doi.org/10.3390/universe9090398 - 30 Aug 2023

Viewed by 630

Hartree–Fock equations in semi-infinite nuclear matter for finite range Gogny interactions are presented together with a detailed numerical scheme to solve them. The value of the surface energy is then extracted and given for standard Gogny interactions. Full article

(This article belongs to the Special Issue Many Body Theory)

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18 pages, 498 KiB

Open AccessArticle

Properties of Hot Nuclear Matter

by Omar Benhar, Alessandro Lovato and Lucas Tonetto

Universe 2023, 9(8), 345; https://doi.org/10.3390/universe9080345 - 25 Jul 2023

Viewed by 537

Abstract

A fully quantitative description of the equilibrium and dynamical properties of hot nuclear matter will be needed for the interpretation of the available and forthcoming astrophysical data, providing information on the post-merger phase of a neutron star coalescence. We discuss the results of [...] Read more.

A fully quantitative description of the equilibrium and dynamical properties of hot nuclear matter will be needed for the interpretation of the available and forthcoming astrophysical data, providing information on the post-merger phase of a neutron star coalescence. We discuss the results of a recently developed theoretical model, based on a phenomenological nuclear Hamiltonian including two- and three-nucleon potentials, to study the temperature dependence of average and single-particle properties of nuclear matter relevant to astrophysical applications. The potential of the proposed approach for describing dissipative processes leading to the appearance of bulk viscosity in neutron star matter is also outlined. Full article

(This article belongs to the Special Issue Many Body Theory)

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21 pages, 680 KiB

Open AccessArticle

Weak Neutrino (Antineutrino) Charged-Current Responses and Scaling for Nuclear Matter in the Relativistic Mean Field

by Sara Cruz-Barrios, Guillermo D. Megias and Juan A. Caballero

Universe 2023, 9(5), 240; https://doi.org/10.3390/universe9050240 - 19 May 2023

Viewed by 745

Abstract

A systematic analysis of the weak responses for charged-current quasielastic neutrino-nucleus reactions is presented within the scheme of a fully relativistic microscopic model considering momentum-dependent scalar and vector mean field potentials in both the initial and final nucleon states. The responses obtained are [...] Read more.

A systematic analysis of the weak responses for charged-current quasielastic neutrino-nucleus reactions is presented within the scheme of a fully relativistic microscopic model considering momentum-dependent scalar and vector mean field potentials in both the initial and final nucleon states. The responses obtained are compared with the ones corresponding to simpler approaches: energy-independent potentials and the relativistic plane wave limit in the final state, i.e., no potentials applied to the outgoing particle. The analysis is also extended to the scaling phenomenon, which provides additional information regarding nuclear dynamics. Results for the scaling function are shown for various nuclei and different values of the transferred momentum in order to analyze the behavior of the relativistic scalar and vector mean field potentials. Full article

(This article belongs to the Special Issue Many Body Theory)

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20 pages, 2481 KiB

Open AccessEditor’s ChoiceArticle

Cross Sections for Coherent Elastic and Inelastic Neutrino-Nucleus Scattering

by Nils Van Dessel, Vishvas Pandey, Heather Ray and Natalie Jachowicz

Universe 2023, 9(5), 207; https://doi.org/10.3390/universe9050207 - 25 Apr 2023

Cited by 2 | Viewed by 1463

Abstract

The prospects of extracting new physics signals in coherent elastic neutrino–nucleus scattering (CE

ν

NS) processes are limited by the precision with which the underlying nuclear structure physics, embedded in the weak nuclear form factor, is known. We present calculations of charge and [...] Read more.

The prospects of extracting new physics signals in coherent elastic neutrino–nucleus scattering (CE

ν

NS) processes are limited by the precision with which the underlying nuclear structure physics, embedded in the weak nuclear form factor, is known. We present calculations of charge and weak nuclear form factors and CE

ν

NS cross sections on

^{12}

C,

^{16}

O,

^{40}

Ar,

^{56}

Fe and

^{208}

Pb nuclei. We obtain the proton and neutron densities, and charge and weak form factors by solving Hartree–Fock (HF) equations with a Skyrme (SkE2) nuclear potential. We validate our approach by comparing

^{208}

Pb and

^{40}

Ar charge form factor predictions with available elastic electron scattering data. Since CE

ν

NS experiments at stopped-pion sources are also well suited to measure inelastic charged–current and neutral–current neutrino–nucleus cross sections, we also present calculations for these processes, incorporating a continuum Random Phase Approximation (CRPA) description on top of the HF–SkE2 picture of the nucleus. Providing both coherent as well as inelastic cross sections in a consistent framework, we aim at obtaining a reliable and detailed comparison of the strength of these processes in the energy region below 100 MeV. Furthermore, we attempt to gauge the level of theoretical uncertainty pertaining to the description of the

^{40}

Ar form factor and CE

ν

NS cross sections by comparing relative differences between recent microscopic nuclear theory and widely-used phenomenological form factor predictions. Future precision measurements of CE

ν

NS will potentially help in constraining these nuclear structure details that will in turn improve prospects of extracting new physics. Full article

(This article belongs to the Special Issue Many Body Theory)

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20 pages, 639 KiB

Open AccessArticle

Improved Superscaling in Quasielastic Electron Scattering with Relativistic Effective Mass

by Paloma Rodriguez Casale, Jose E. Amaro, Victor L. Martinez-Consentino and Ignacio Ruiz Simo

Universe 2023, 9(4), 158; https://doi.org/10.3390/universe9040158 - 24 Mar 2023

Cited by 3 | Viewed by 1031

Abstract

Superscaling in electron scattering from nuclei is re-examined, paying special attention to the definition of the averaged single-nucleon responses. The validity of the extrapolation of nucleon responses in the Fermi gas has been examined, which previously lacked a theoretical foundation. To address this [...] Read more.

Superscaling in electron scattering from nuclei is re-examined, paying special attention to the definition of the averaged single-nucleon responses. The validity of the extrapolation of nucleon responses in the Fermi gas has been examined, which previously lacked a theoretical foundation. To address this issue, we introduce new averaged responses with a momentum distribution smeared around the Fermi surface, allowing for momenta above the Fermi momentum. This approach solves the problem of negativity in the extrapolation away from the scaling region and, at the same time, validates its use in the scaling analysis. This work has important implications for the interpretation of scaling data and contributes to the development of a more complete understanding of the scaling approach. Full article

(This article belongs to the Special Issue Many Body Theory)

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Review

Jump to: Research, Other

27 pages, 3402 KiB

Open AccessReview

Lepton–Nucleus Interactions within Microscopic Approaches

by Alessandro Lovato, Alexis Nikolakopoulos, Noemi Rocco and Noah Steinberg

Universe 2023, 9(8), 367; https://doi.org/10.3390/universe9080367 - 09 Aug 2023

Cited by 5 | Viewed by 1672

Abstract

This review paper emphasizes the significance of microscopic calculations with quantified theoretical error estimates in studying lepton–nucleus interactions and their implications for electron scattering and accelerator neutrino oscillation measurements. We investigate two approaches: Green’s Function Monte Carlo and the extended factorization scheme, utilizing [...] Read more.

This review paper emphasizes the significance of microscopic calculations with quantified theoretical error estimates in studying lepton–nucleus interactions and their implications for electron scattering and accelerator neutrino oscillation measurements. We investigate two approaches: Green’s Function Monte Carlo and the extended factorization scheme, utilizing realistic nuclear target spectral functions. In our study, we include relativistic effects in Green’s Function Monte Carlo and validate the inclusive electron scattering cross section on carbon using available data. We compare the flux-folded cross sections for neutrino-carbon scattering with T2K and MINER

ν

A experiments, noting the substantial impact of relativistic effects in reducing the theoretical curve strength when compared to MINER

ν

A data. Additionally, we demonstrate that quantum Monte Carlo-based spectral functions accurately reproduce the quasi-elastic region in electron scattering data and T2K flux-folded cross sections. By comparing results from Green’s Function Monte Carlo and the spectral function approach, which share a similar initial target state description, we quantify errors associated with approximations in the factorization scheme and the relativistic treatment of kinematics in Green’s Function Monte Carlo. Full article

(This article belongs to the Special Issue Many Body Theory)

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36 pages, 702 KiB

Open AccessReview

by Guy Chanfray, Magda Ericson and Marco Martini

Universe 2023, 9(7), 316; https://doi.org/10.3390/universe9070316 - 30 Jun 2023

Cited by 2 | Viewed by 641

Abstract

We study the role of short-range correlations, as well as pion and rho loops governing long-range RPA correlations, in nuclear matter properties and response functions. We use an adapted formulation of the Brueckner G-matrix approach to generate a pair correlation function satisfying [...] Read more.

We study the role of short-range correlations, as well as pion and rho loops governing long-range RPA correlations, in nuclear matter properties and response functions. We use an adapted formulation of the Brueckner G-matrix approach to generate a pair correlation function satisfying the Beg–Agassi–Gal theorem, providing a natural cutoff to the loop integrals. We present results for the case of a relativistic chiral theory, including the effects of quark confinement and of the chirally broken vacuum in a version where parameters are directly connected to QCD observables or constrained by well-established hadron phenomenology. This provides a unified and coherent view of the nuclear matter equation of state and the effect of correlations on neutrino–nucleus scattering. Full article

(This article belongs to the Special Issue Many Body Theory)

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61 pages, 650 KiB

Open AccessReview

Introducing the Random Phase Approximation Theory

by Giampaolo Co’

Universe 2023, 9(3), 141; https://doi.org/10.3390/universe9030141 - 07 Mar 2023

Cited by 4 | Viewed by 3322

Abstract

Random Phase Approximation (RPA) is the theory most commonly used to describe the excitations of many-body systems. In this article, the secular equations of the theory are obtained by using three different approaches: the equation of motion method, the Green function perturbation theory [...] Read more.

Random Phase Approximation (RPA) is the theory most commonly used to describe the excitations of many-body systems. In this article, the secular equations of the theory are obtained by using three different approaches: the equation of motion method, the Green function perturbation theory and the time-dependent Hartree–Fock theory. Each approach emphasizes specific aspects of the theory overlooked by the other methods. Extensions of the RPA secular equations to treat the continuum part of the excitation spectrum and also the pairing between the particles composing the system are presented. Theoretical approaches which overcome the intrinsic approximations of RPA are outlined. Full article

(This article belongs to the Special Issue Many Body Theory)

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Other

Jump to: Research, Review

13 pages, 412 KiB

Open AccessPerspective

High-Energy Lepton Scattering and Nuclear Structure Issues

by Thomas W. Donnelly

Universe 2023, 9(4), 196; https://doi.org/10.3390/universe9040196 - 20 Apr 2023

Cited by 1 | Viewed by 856

Abstract

High-energy lepton scattering constitutes the focus of this study. Developments are provided to motivate the basic choices of kinematic variables for the particular case of semi-inclusive electron scattering where these variables are devised to match well with the underlying dynamics to be expected [...] Read more.

High-energy lepton scattering constitutes the focus of this study. Developments are provided to motivate the basic choices of kinematic variables for the particular case of semi-inclusive electron scattering where these variables are devised to match well with the underlying dynamics to be expected for the general “nuclear landscape”. Various nuclear structure issues and other issues related to the nature of the electroweak currents at high energies are then discussed, as are some of the issues related to the different conditions occurring for electron scattering versus what is typically the case for charge-changing neutrino reactions. Full article

(This article belongs to the Special Issue Many Body Theory)

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