Nuclear Theory·nucl-th

Tuesday·March 23, 2021

13 papers—5 primary·8 cross-listed

01
[Submitted on 20 Mar 2021]
Study of resonances in exotic drip-line nuclei by the use of super-symmetric quantum mechanics
Md. A. Khan🇮🇳 · M. Hasan🇮🇳 · S. H. Mondal🇮🇳 · M. Alam🇮🇳 · T. Surungan
In this paper, a nice theoretical scheme is presented to investigate resonant and bound states in weakly bound nuclear systems by the use of isospectral potentials together with hyperspherical harmonics expansion. In this scheme, a new potential is constructed which is strictly isospectral with the original shallow potential and has properties that are desirable to calculate resonances more accurately and elegantly. The effectiveness of the method has been checked in terms of its application to the $0^{+}$ resonances in the neutron-rich isotopes $^{18, 20}$ C in the two-neutron plus core three-body cluster model. The results are in excellent agreement with the available data.
Comments:
18 pages, 12 figures, 5 tables. arXiv admin note: substantial text overlap with arXiv:2010.01585
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2103.11153 [pdf]
0 citations
02
[Submitted on 20 Mar 2021]
Model of Energy Dependent Total, Absorption, and 3He and 3H Production Cross Sections in 4He-proton Collisions
Congchong Yan🇨🇳 · Premkumar B. Saganti🇺🇸 · Francis A. Cucinotta🇺🇸
Light ion (A<5) breakup cross sections are important for studies of cosmic ray interactions in the inter-stellar medium or radiation protection considerations of energy deposition in tissue. Nucleon abrasion cross sections for heavy ion reactions are often calculated using the Glauber model in the large mass limit or with the Eikonal form of the optical potential model. Here we formulate an abrasion model for 4He nuclei fragmentation on hydrogen targets with a classical model for final state interactions. Comparisons to the heavy ion abrasion model are made. Calculations of energy dependent total, absorption, elastic and breakup cross sections for 4He into 3He or 3H with protons targets are shown to be in good agreement with experimental measurements for energies from 100 to 100,000 MeV/u. The Glauber model for light nuclei and the large mass limit to the model are shown to be in close agreement for 4He-proton interactions above 300 MeV/u, however important differences occur at lower energies.
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2103.11162 [pdf]
Nucl.Instrum.Meth.B(2021)·1 citation
03
[Submitted on 22 Mar 2021]
Magneto-vortical Effect in Strong Magnetic Field
Shu Lin🇨🇳 · Lixin Yang🇨🇳
We develop covariant chiral kinetic theory with Landau level basis. We use it to investigate a magnetized plasma with a transverse electric field and a steady vorticity as perturbations. After taking into account vacuum shift in the latter case, we find the resulting current and stress tensor in both cases can be matched consistently with constitutive equations of magnetohydrodynamics. We find the solution in the vorticity case contains both shifts in temperature and chemical potential as well as excitations of the lowest Landau level states. The solution gives rise to an vector charge density and axial current density. The vacuum parts coming from both shifts and excitations agree with previous studies and the medium parts coming entirely from excitations leads to a new contribution to vector charge and axial current density consistent with standard chiral vortical effect.
Comments:
29 pages, no figures
Subjects:
Nuclear Theory (nucl-th); Mesoscale and Nanoscale Physics (cond-mat.mes-hall); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2103.11577 [pdf]
JHEP(2021)·15 citations
04
[Submitted on 22 Mar 2021]
Direct and sequential four-body recombination rates at low temperatures
E. Garrido · A.S. Jensen
We investigate four-body nuclear reactions in stellar environments contributing to creation of light nuclei, exemplified by $^{9}$ Be and $^{12}$ C. The originally assumed process is radiative capture, where nuclear clusters combine into the excited final nucleus and photon emission populates the stable nuclear ground states. Instead, we consider nuclear four-body recombination reactions where a spectator nuclear particle replaces the photon. We first develop the elaborate formalism for both, direct and sequential capture processes, where the decaying three-body resonance is formed without and with population of an intermediate two-body resonance, respectively. To facilitate both calculations and practical applications we parameterize the involved cross sections as done successfully in previous computations of reaction rates. We consider the lowest-lying nuclear states with their dominant contributions at low stellar temperatures. We calculate and compare reaction and production rates for different processes. The direct reaction mechanism dominates by many orders of magnitude at low temperature, where the sequential stepping stones are energetically too expensive to use. At somewhat higher temperatures these two different nuclear four-body mechanisms become comparable. Comparison to radiative three-body capture reveals already formally, but also numerically, that four-body nuclear recombination must dominate for sufficiently high nuclear densities. Numerical values are given for all these rates as function of temperature and density. The relative importance is exhibited.
Comments:
12 pages, 6 figures. Submitted for publication
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
2103.11973 [pdf]
PRC(2021)·2 citations
05
[Submitted on 22 Mar 2021]
Cluster structure of 21Ne and 21Na
R. Bijker🇲🇽 · F. Iachello🇺🇸
We study the cluster structure of 21Ne and 21Na within the framework of the cluster shell model (CSM) and show that they have a complex cluster structure with the coexistence of a 20Ne+n, 20}Ne+p structure and a 19Ne+2n, 19}F+2p structure. Seven rotational bands are identified in 21Ne and four in 21Na and assigned to single-particle cluster states, single-hole cluster states and vibrational states. The single-particle states are associated with the 20Ne+n and 20Ne+p cluster structure, while the single-hole states are associated with the 19Ne+2n and 19F+2p structure.
Comments:
32 pages, 8 figures, 18 tables, accepted for publication in Nuclear Physics A
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2103.12014 [pdf]
NPA(2021)·7 citations
06
[Submitted on 20 Mar 2021] (cross-list from hep-ph)
Evolution of Primordial Neutrino Helicities in Cosmic Gravitational Inhomogeneities
Gordon Baym🇺🇸 · Jen-Chieh Peng🇺🇸
Relic neutrinos from the Big Bang decoupled from the hot plasma predominantly in helicity eigenstates. Their subsequent propagation through gravitational inhomogeneities of the Universe alters the helicities of both Dirac and Majorana neutrinos, thus providing an independent probe of the evolving universe. We determine here the probability that relic neutrinos flip their helicity, in terms of the spectrum of density inhomogeneities measured in the Cosmic Microwave Background. As we find, for Dirac neutrinos the gravitational helicity modifications are intermediate between the effects of magnetic fields if the neutrino magnetic moment is of the magnitude predicted in the Standard Model and the much larger effects if the magnetic moment is of the scale consistent with the excess of low energy electron events seen by the XENON1T experiment. We give succinct derivations, within general relativity, of the semi-classical response of a spinning particle to a weak gravitational field in an expanding universe, and estimate the helicity modifications of neutrinos emitted by the Sun caused by the Sun's gravity.
Comments:
Typographical error corrected in Appendix A
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.11209 [pdf]
PRD(2021)·21 citations
07
[Submitted on 20 Mar 2021] (cross-list from astro-ph.HE)
Nuclear-powered X-ray millisecond pulsars
Sudip Bhattacharyya (TIFR, India)
Nuclear-powered X-ray millisecond pulsars are the third type of millisecond pulsars, which are powered by thermonuclear fusion processes. The corresponding brightness oscillations, known as burst oscillations, are observed during some thermonuclear X-ray bursts, when the burning and cooling accreted matter gives rise to an azimuthally asymmetric brightness pattern on the surface of the spinning neutron star. Apart from providing neutron star spin rates, this X-ray timing feature can be a useful tool to probe the fundamental physics of neutron star interior and surface. This chapter presents an overview of the relatively new field of nuclear-powered X-ray millisecond pulsars.
Comments:
Preprint of a chapter of the book 'Millisecond Pulsars', of the Astrophysics and Space Science Library (ASSL) series edited by Sudip Bhattacharyya, Alessandro Papitto and Dipankar Bhattacharya; 26 pages, 5 figures, 2 tables
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.11258 [pdf]
Astrophys.Space Sci.Libr.(2021)·15 citations
08
[Submitted on 21 Mar 2021] (cross-list from cond-mat.stat-mech)
Functional-renormalization-group approach to classical liquids with short-range repulsion: a scheme without repulsive reference system
Takeru Yokota🇯🇵 · Jun Haruyama🇯🇵 · Osamu Sugino🇯🇵
The renormalization-group approaches for classical liquids in previous works require a repulsive reference such as a hard-core one when applied to systems with short-range repulsion. The need for the reference is circumvented here by using a functional renormalization group approach for integrating the hierarchical flow of correlation functions along a path of variable interatomic coupling. We introduce the cavity distribution functions to avoid the appearance of divergent terms and choose a path to reduce the error caused by the decomposition of higher order correlation functions. We demonstrate using an exactly solvable one-dimensional models that the resulting scheme yields accurate thermodynamic properties and interatomic distribution at various densities when compared to integral-equation methods such as the hypernetted chain and the Percus-Yevick equation, even in the case where our hierarchical equations are truncated with the Kirkwood superposition approximation, which is valid for low-density cases.
Comments:
17 pages, 7 figures, v2: some sentences added, some subsections added, minor modifications for figures and sentences made, references added
Subjects:
Statistical Mechanics (cond-mat.stat-mech); cond-mat.soft (cond-mat.soft); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2103.11375 [pdf]
PRE(2021)·8 citations
09
[Submitted on 21 Mar 2021] (cross-list from hep-ph)
Dynamical Phase Transitions in models of Collective Neutrino Oscillations
Alessandro Roggero🇺🇸
Collective neutrino oscillations can potentially play an important role in transporting lepton flavor in astrophysical scenarios where the neutrino density is large, typical examples are the early universe and supernova explosions. It has been argued in the past that simple models of the neutrino Hamiltonian designed to describe forward scattering can support substantial flavor evolution on very short time scales $t \approx lo g (N) / (G_{F} ρ_{ν})$ , with $N$ the number of neutrinos, $G_{F}$ the Fermi constant and $ρ_{ν}$ the neutrino density. This finding is in tension with results for similar but exactly solvable models for which $t \approx N / (G_{F} ρ_{ν})$ instead. In this work we provide a coherent explanation of this tension in terms of Dynamical Phase Transitions (DPT) and study the possible impact that a DPT could have in more realistic models of neutrino oscillations and their mean-field approximation.
Comments:
13 pages, 9 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2103.11497 [pdf]
PRD(2021)·54 citations
10
[Submitted on 21 Mar 2021] (cross-list from hep-ph)
QCD Analysis of Near-Threshold Photon-Proton Production of Heavy Quarkonium
Yuxun Guo🇺🇸 · Xiangdong Ji🇺🇸 · Yizhuang Liu🇩🇪
The near threshold photo or electroproduction of heavy vector quarkonium off the proton is studied in quantum chromodynamics. Similar to the high-energy limit, the production amplitude can be factorized in terms of gluonic Generalized Parton Distributions and the quarkonium distribution amplitude. At the threshold, the threshold kinematics has a large skewness parameter $ξ$ , leading to the dominance of the spin-2 contribution over higher-spin twist-2 operators. Thus threshold production data are useful to extract the gluonic gravitational form factors, allowing studying the gluonic contributions to the quantum anomalous energy, mass radius, spin and mechanical pressure in the proton. We use the recent GlueX data on the $J / ψ$ photoproduction to illustrate the potential physics impact from the high-precision data from future JLab 12 GeV and EIC physics program.
Comments:
11 pages, 10 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.11506 [pdf]
PRD(2021)·112 citations
11
[Submitted on 22 Mar 2021] (cross-list from hep-ph)
Thermal impacts on the properties of nuclear matter and young neutron star
Ankit Kumar🇮🇳 · H. C. Das🇮🇳 · M. Bhuyan🇲🇾 · S. K. Patra🇮🇳
We present a methodical study of the thermal and nuclear properties for the hot nuclear matter using relativistic-mean field theory. We examine the effects of temperature on the binding energy, pressure, thermal index, symmetry energy, and its derivative for the symmetric nuclear matter using temperature-dependent relativistic mean-field formalism for the well-known G2 $^{*}$ and recently developed IOPB-I parameter sets. The critical temperature for the liquid-gas phase transition in an asymmetric nuclear matter system has also been calculated and collated with the experimentally available data. We investigate the approach of the thermal index as a function of nucleon density in the wake of relativistic and non-relativistic formalism. The computation of neutrino emissivity through the direct Urca process for the supernovae remnants has also been performed, which manifests some exciting results about the thermal stabilization and evolution of the newly born proto-neutron star. The central temperature and the maximum mass of the proto-neutron star have also been calculated for different entropy values.
Comments:
11 pages, 8 figures, aacpeted for publication in Nuclear Physics A
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
arXiv:
2103.11635 [pdf]
NPA(2021)·3 citations
12
[Submitted on 22 Mar 2021] (cross-list from hep-ph)
Correlating Non-Resonant Di-Electron Searches at the LHC to the Cabibbo-Angle Anomaly and Lepton Flavour Universality Violation
Andreas Crivellin🇨🇭 · Claudio Andrea Manzari🇨🇭 · Marc Montull🇨🇭
In addition to the existing strong indications for lepton flavour university violation (LFUV) in low energy precision experiments, CMS recently released an analysis of non-resonant di-lepton pairs which could constitute the first sign of LFUV in high-energy LHC searches. In this article we show that the Cabibbo angle anomaly, an (apparent) violation of first row and column CKM unitarity with $\approx 3 σ$ significance, and the CMS result can be correlated and commonly explained in a model independent way by the operator $[Q_{ℓ q}^{(3)}]_{1111} = (ℓ ˉ_{1} γ^{μ} σ^{I} ℓ_{1}) (q ˉ_{1} γ_{μ} σ^{I} q_{1})$ . This is possible without violating the bounds from the non-resonant di-lepton search of ATLAS (which interestingly also observed slightly more events than expected in the electron channel) nor from $R (π) = π \to μν / π \to e ν$ . We find a combined preference for the new physics hypothesis of $4.5 σ$ and predict $1.0004 < R (π) < 1.0009$ (95\%~CL) which can be tested in the near future with the forthcoming results of the PEN experiment.
Comments:
6 pages, 2 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.12003 [pdf]
PRD(2021)·36 citations
13
[Submitted on 22 Mar 2021] (cross-list from hep-ph)
Perturbative QCD Analysis of Near Threshold Heavy Quarkonium Photoproduction at Large Momentum Transfer
Peng Sun🇨🇳 · Xuan-Bo Tong🇨🇳 · Feng Yuan🇺🇸
We apply perturbative QCD to investigate the near threshold heavy quarkonium photoproduction at large momentum transfer. From an explicit calculation, we show that the conventional power counting method will be modified and the three quark Fock state with nonzero orbital angular momentum dominates the near threshold production. It carries a power behavior of $1/ (- t)^{5}$ for the differential cross section. We further comment on the impact of our results on the interpretation of the experiment measurement in terms of the gluonic gravitational form factors of the proton.
Comments:
fig.2 updated, references added; 6 pages, 3 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2103.12047 [pdf]
PLB(2021)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE