Nuclear Theory·nucl-th

Friday·June 19, 2020

6 papers—3 primary·3 cross-listed

01
Microscopic Calculation of $Λ - α$ Folding Potential
Htun Htun Oo🇲🇲 · Hiroyuki Kamada🇯🇵
We construct a folding potential between the $α$ and $Λ$ particles based on underlying nucleon-nucleon and hyperon-nucleon interactions. Starting from a phenomenological $Λ$ -N potential and a Gaussian form of the $α$ -particle wave function we obtain for the built $α$ - $Λ$ interaction a bound $_{Λ}^{5}$ He state with the binding energy (3.10 MeV), which is consistent with recent experimental data $3.12 \pm 0.02$ MeV. When in turn an exact solution of the four-body Faddeev-Yakubovsky equation for the $α$ -particle calculated with the CDBonn, Nijmegen or Argonne V18 realistic nucleon-nucleon potential is used and the phenomenological Gaussian $Λ$ -N potential is replaced by the realistic (Nijmegen NSC97f) potential approximated by a rank-1 separable form, then $_{Λ}^{5}$ He is overbound. In particular, its binding energy given by the folding potential generated with the $α$ particle wave function based on the CDBonn potential is 7.47 MeV. Although the rank-1 separable $Λ$ -N potential reproduces the exact scattering length and the effective range of the original $Λ$ -N potential, the overbinding results from the lack of the required repulsive properties in the assumed separable form.
nucl-thFew Body Syst.(2022)·0 citations
02
Spectral functions of strange vector mesons in asymmetric hyperonic matter
Amruta Mishra🇮🇳 · S. P. Misra🇮🇳
We study the medium modifications of the spectral functions as well as production cross-sections of the strange vector mesons ( $ϕ$ , $K^{*}$ and $K^{*} ˉ$ ) in isospin asymmetric strange hadronic matter. These are obtained from the in-medium masses of the open strange mesons and the decay widths $ϕ \to K K ˉ$ , $K^{*} \to K π$ and $K^{*} ˉ \to K ˉ π$ in the hadronic medium. The decay widths are computed using a field theoretic model of composite hadrons with quark/antiquark constituents, from the matrix element of the light quark-antiquark pair creation term of the free Dirac Hamiltonian between the initial and final states. The matrix element is multiplied with a coupling strength parameter for the light quark-antiquark pair creation, which is fitted to the observed vacuum decay width of the decay process. There are observed to be substantial modifications of the spectral functions as well as production cross-sections of these vector mesons due to isospin asymmetry as well as strangeness of the hadronic medum at high densities. These studies should have observable consequences, e.g. in the yield of the hidden and open strange mesons arising from the isospin asymmetric high energy heavy ion collisions at the Compressed baryonic matter (CBM) experiments at the future facility at GSI.
nucl-thhep-phEPJA(2021)·7 citations
03
Green's functions techniques for extended nuclear systems
A. Rios
I review the application of self-consistent Green's functions methods to study the properties of infinite nuclear systems. Improvements over the last decade, including the consistent treatment of three-nucleon forces and the development of extrapolation methods from finite to zero temperature, have allowed for realistic predictions of the equation of state of infinite symmetric, asymmetric and neutron matter based on chiral interactions. Microscopic properties, like momentum distributions or spectral functions, are also accessible. Using an indicative set of results based on a subset of chiral interactions, I summarise here the first-principles description of infinite nuclear system provided by Green's functions techniques, in the context of several issues of relevance for nuclear theory including, but not limited to, the role of short-range correlations in nuclear systems, nuclear phase transitions and the isospin dependence of nuclear observables.
nucl-thFront.in Phys.(2020)·39 citations
04
Short-Range Correlations and the Nuclear EMC Effect in Deuterium and Helium-3
E.P. Segarra🇺🇸 · J.R. Pybus🇺🇸 · F. Hauenstein🇺🇸 · D.W. Higinbotham🇺🇸 · G.A. Miller🇺🇸 · E. Piasetzky🇮🇱 · A. Schmidt🇺🇸 · M. Strikman🇺🇸 · L.B. Weinstein🇺🇸 · O. Hen🇺🇸
The EMC effect in deuterium and helium-3 is studied using a convolution formalism that allows isolating the impact of high-momentum nucleons in short-ranged correlated (SRC) pairs. We assume that the modification of the structure function of bound nucleons is given by a universal (i.e. nucleus independent) function of their virtuality, and find that the effect of such modifications is dominated by nucleons in SRC pairs. This SRC-dominance of nucleon modifications is observed despite the fact that the bulk of the nuclear inelastic scattering cross-section comes from interacting with low-momentum nucleons. These findings are found to be robust to model details including nucleon modification function parametrization, free nucleon structure function and treatment of nucleon motion effects. While existing data cannot discriminate between such model details, we present predictions for measured, but not yet published, tritium EMC effect and tagged nucleon structure functions in deuterium that are sensitive to the neutron structure functions and bound nucleon modification functions.
↳ hep-phhep-exnucl-exnucl-thPRResearch(2021)·15 citations
05
Elimination of the effect of internal activity in LaCl3:Ce scintillator
D. Chattopadhyay · Sathi Sharma · M. Saha Sarkar
The Lanthanum Halide scintillator detectors have been widely used for nuclear spectroscopy experiments because of their excellent energy and time resolutions. Despite having these advantages, the intrinsic alpha and beta contaminations in these scintillators pose a severe limitation in their usage in rare-event detections. In the present work, pulse shape discrimination (PSD) with a fast digitizer has been shown to be an efficient method to separate the effect of alpha contamination from the spectrum. The shape of the beta spectrum has been generated with the help of Monte Carlo based simulation code, and its contribution has been eliminated from the spectrum. The reduction in the background events generated by both intrinsic beta and alpha activities has been demonstrated. The present study will encourage the application of these detectors in low cross-section measurement experiments relevant to nuclear astrophysics.
↳ physics.ins-detnucl-exnucl-thJINST(2021)·0 citations
06
Gamow-Teller transitions and the spin EMC effect: the Bjorken sum-rule in medium
Steven D. Bass🇦🇹
Gamow-Teller transitions in nuclei tell us that the nucleon's axial charge $g_{A}^{(3)}$ is quenched in large nuclei by about 20%. This result tells us that the spin structure of the nucleon is modified in nuclei and disfavours models of the medium dependence of parton structure based only on nucleon short range correlations in nuclei. For polarized photoproduction the Gerasimov-Drell-Hearn integral is expected to be strongly enhanced in medium.
↳ hep-phnucl-thActa Phys.Polon.B(2021)·10 citations

Affiliations

first authorsco-authorsvia INSPIRE

Microscopic Calculation of Λ−α Folding Potential

Spectral functions of strange vector mesons in asymmetric hyperonic matter

Green's functions techniques for extended nuclear systems

Short-Range Correlations and the Nuclear EMC Effect in Deuterium and Helium-3

Elimination of the effect of internal activity in LaCl3:Ce scintillator

Gamow-Teller transitions and the spin EMC effect: the Bjorken sum-rule in medium

Affiliations

Microscopic Calculation of $Λ - α$ Folding Potential