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Nuclear Theory·nucl-th

Friday·January 12, 2024

15 papers—8 primary·7 cross-listed

All15Primary8Cross-lists7
  1. 09

    [Submitted on 9 Jan 2024] (cross-list from physics.plasm-ph)

    Effect of Longitudinal Fluctuations of D Weizsäcker-Williams Field on Pressure Isotropization of Glasma

    Hidefumi Matsuda🇨🇳 · Xu-Guang Huang🇨🇳

    We investigate the effects of boost invariance breaking on the isotropization of pressure in the glasma, using the D glasma simulation. The breaking is attributed to spatial fluctuations of the classical color charge density along the collision axis. We present numerical results for pressure and energy density at mid-rapidity and across a wider rapidity region. It is found that, despite varying longitudinal correlation lengths, the behaviors of the pressure isotropizations are qualitatively similar. The numerical results suggest that, in the initial stage, longitudinal color electromagnetic fields develop, similar to those in the boost invariant glasma. Subsequently, these fields evolve into a dilute glasma, expanding longitudinally in a manner akin to a dilute gas. We also show that the energy density at mid-rapidity exhibits a decay in the dilute glasma stage.

    Comments:
    16 page, 6 figures
    Subjects:
    Plasma Physics (physics.plasm-ph); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2401.04296 [pdf]
    Entropy(2024)·9 citations
  2. 10

    [Submitted on 10 Jan 2024] (cross-list from hep-lat)

    Trace anomaly form factors from lattice QCD

    Bigeng Wang🇺🇸 · Fangcheng He🇺🇸 · Gen Wang🇫🇷 · Terrence Draper🇺🇸 · Jian Liang🇨🇳 · Keh-Fei Liu🇺🇸 · Yi-Bo Yang🇨🇳

    The hadron mass can be obtained through the calculation of the trace of the energy-momentum tensor in the hadron which includes the trace anomaly and sigma terms. The anomaly due to conformal symmetry breaking is believed to be an important ingredient for hadron mass generation and confinement. In this work, we will present the calculation of the glue part of the trace anomaly form factors of the pion up to and the nucleon up to . The calculations are performed on a domain wall fermion ensemble with overlap valence quarks at seven valence pion masses varying from to MeV, including the unitary point MeV. We calculate the radius of the glue trace anomaly for the pion and the nucleon from the expansion. By performing a two-dimensional Fourier transform on the glue trace anomaly form factors in the infinite momentum frame with no energy transfer, we also obtain their spatial distributions for several valence quark masses. The results are qualitatively extrapolated to the physical valence pion mass with systematic errors from the unphysical sea quark mass, discretization effects in the renormalization sum rule, and finite-volume effects to be addressed in the future. We find the pion's form factor changes sign, as does its spatial distribution, for light quark masses. This explains how the trace anomaly contribution to the pion mass approaches zero toward the chiral limit.

    Comments:
    This is the version accepted for publication in Physical Review D
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2401.05496 [pdf]
    PRD(2024)·35 citations
  3. 11

    [Submitted on 10 Jan 2024] (cross-list from hep-ph)

    Orbital Angular Momentum Small- Evolution: Exact Results in the Large- Limit

    Brandon Manley🇺🇸

    We construct an exact solution to the revised small- orbital angular momentum (OAM) evolution equations derived recently, based on an earlier work. These equations are derived in the double logarithmic approximation (summing powers of with the strong coupling constant and the Bjorken variable) and the large- limit, with the number of quark colors. From our solution, we extract the small-, large- expressions of the quark and gluon OAM distributions. Additionally, we determine the large- small- asymptotics of the OAM distributions to be \begin{align} \notag L_{q+\bar{q}}(x,Q^2) \sim L_G(x,Q^2) \sim \Delta \Sigma (x,Q^2) \sim \Delta G(x,Q^2) \sim \left(\frac{1}{x} \right)^{\alpha_h}, \end{align} with the intercept the same as obtained in the small- helicity evolution, which can be approximated as . This result is in complete agreement with the literature. Additionally, we calculate the ratio of the quark and gluon OAM distributions to the flavor-singlet quark and gluon helicity parton distribution functions respectively in the small- region.

    Comments:
    27 pages, 2 figures; v2: typos corrected, references added, appendix C modified, 22 pages, 2 figures. Signs corrected, discussion expanded; v4: typos corrected
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2401.05508 [pdf]
    JHEP(2024)·15 citations
  4. 12

    [Submitted on 11 Jan 2024] (cross-list from astro-ph.HE)

    Astromers: Status and Prospects

    G. Wendell Misch · Matthew R. Mumpower

    The extreme temperatures and densities of many astrophysical environments tends to destabilize nuclear isomers by inducing transitions to higher energy states. Those states may then cascade to ground. However, not all environments destabilize all isomers. Nuclear isomers which retain their metastable character in pertinent astrophysical environments are known as astrophysically metastable nuclear isomers, or "astromers". Astromers can influence nucleosynthesis, altering abundances or even creating new pathways that would otherwise be inaccessible. Astromers may also release energy faster or slower relative to their associated ground state, acting as heating accelerants or batteries, respectively. In stable isotopes, they may even simply remain populated after a cataclysmic event and emit observable x- or -rays. The variety of behaviors of these nuclear species and the effects they can have merit careful consideration in nearly every possible astrophysical environment. Here we provide a brief overview of astromers past and present, and we outline future work that will help to illuminate their role in the cosmos.

    Comments:
    39 pages(10 of the 16 of them references), 5 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2401.05598 [pdf]
    Eur.Phys.J.ST(2024)·13 citations
  5. 13

    [Submitted on 11 Jan 2024] (cross-list from hep-lat)

    Advancing real-time Yang-Mills: towards real-time observables from first principles

    Kirill Boguslavski · Paul Hotzy · David I. Müller🇦🇹

    The complex Langevin (CL) method shows great promise in enabling the calculation of observables for theories with complex actions. Nevertheless, real-time quantum field theories have remained largely unsolved due to the particular severity of the sign problem. In this contribution, we discuss our recent progress in applying CL to a thermal SU(2) Yang-Mills theory on a 3+1 dimensional lattice. We present our anisotropic kernel that stabilizes the CL approach for real times longer than the inverse temperature - a first for Yang-Mills theory. We provide explicit evidence of reproducing symmetries and relations among different types of propagators when the complex time path approaches the Schwinger-Keldysh contour. This method paves the way for calculating transport coefficients and other real-time observables from first principles.

    Comments:
    10 pages, 7 figures; Proceedings of the 40th International Symposium on Lattice Field Theory (LATTICE2023)
    Subjects:
    High Energy Physics — Lattice (hep-lat); cond-mat.other (cond-mat.other); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2401.05723 [pdf]
    PoS(2024)·2 citations
  6. 14

    [Submitted on 11 Jan 2024] (cross-list from physics.atom-ph)

    Full leading-order nuclear polarization in highly charged ions

    Igor A. Valuev · Natalia S. Oreshkina (Max-Planck-Institut für Kernphysik, Heidelberg, Germany)

    The nuclear-polarization corrections to the energy levels of highly charged ions are systematically investigated to leading order in the fine-structure constant. To this end, the notion of effective photon propagators with nuclear-polarization insertions is employed, where the nuclear excitation spectrum is calculated by means of the Hartree-Fock-based random-phase approximation. The effective Skyrme force is used to describe the interaction between nucleons, and the model dependence is analyzed. To leading order, the formalism predicts two contributions given by the effective vacuum-polarization and self-energy diagrams. The existing ambiguity around the vacuum-polarization term is resolved by demonstrating that it is effectively absorbed in the standard finite-nuclear-size correction. The self-energy part is evaluated with the full electromagnetic electron-nucleus interaction taken into account, where the importance of the effects of the nuclear three-currents is emphasized.

    Comments:
    12 pages, 3 figures, 4 tables; typos corrected, Table I and Fig. 3 slightly updated
    Subjects:
    Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2401.05904 [pdf]
    PRA(2024)·11 citations
  7. 15

    [Submitted on 11 Jan 2024] (cross-list from physics.atom-ph)

    The spin-flip-induced quadrupole resonance in odd- exotic atoms

    Fredrik P. Gustafsson🇨🇭 · Daniel Pęcak🇵🇱 · Tomasz Sowiński🇵🇱

    We examine the possible existence of quadrupole resonances in exotic atoms containing odd- nuclei. We find that the spin-flip of the de-exciting exotic particle can induce a resonance, altering the orbital angular momentum of the nucleus by one quanta. This process results in an excited nucleus with a suppression in x-ray photon emissions during the exotic atom cascade. We provide specific cases of antiprotonic atoms of stable elements where this resonance effect is expected to occur. The study of this phenomena may provide insight into the strong interaction of deeply bound antiprotonic states in the proximity of the unpaired nucleon, and serve as a tool for probing short-lived excited nuclear states.

    Subjects:
    Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th)
    arXiv:
    2401.06063 [pdf]
    PRC(2024)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE