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Nuclear Theory·nucl-th

Monday·April 8, 2024

9 papers—2 primary·7 cross-listed

All9Primary2Cross-lists7
  1. 03

    [Submitted on 26 Mar 2024] (cross-list from hep-ph)

    Target normal single-spin asymmetry in inclusive electron-nucleon scattering in the 1/Nc expansion

    Jose L. Goity · Christian Weiss

    The target normal single-spin asymmetry in electron nucleon scattering is studied in the framework of the 1/Nc expansion of QCD, which allows for a rigorous description in the energy range that includes the Delta resonance and below the second baryon resonance region. The asymmetry is driven by the absorptive part of the two-photon exchange component of the scattering amplitude, being therefore the most unambiguous two-photon exchange effect. Such amplitude is shown to be described up to the next to leading order in the 1/Nc expansion only in terms of the charge and magnetic form factors of the nucleons, consequence of the approximate spin flavor symmetry valid in the large Nc limit for baryons. A discussion is provided of the 1/Nc expansion framework along with the results for the asymmetries in elastic, inelastic, and inclusive electron-nucleon scattering.

    Comments:
    13 pages, 5 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2404.03674 [pdf]
    0 citations
  2. 04

    [Submitted on 3 Apr 2024] (cross-list from astro-ph.HE)

    Nuclear uncertainties associated with the ejecta of a neutron-star black-hole accretion disk

    M. R. Mumpower · T. M. Sprouse · J. M. Miller · K. A. Lund · J. Cabrera Garcia · N. Vassh · G. C. McLaughlin · R. Surman

    The simulation of heavy element nucleosynthesis requires input from yet-to-be-measured nuclear properties. The uncertainty in the values of these off-stability nuclear properties propagates to uncertainties in the predictions of elemental and isotopic abundances. However, for any given astrophysical explosion, there are many different trajectories, i.e. temperature and density histories, experienced by outflowing material and thus different nuclear properties can come into play. We consider combined nucleosynthesis results from 460,000 trajectories from a neutron star-black hole accretion disk and the find spread in elemental predictions due solely to unknown nuclear properties to be a factor of a few. We analyze this relative spread in model predictions due to nuclear variations and conclude that the uncertainties can be attributed to a combination of properties in a given region of the abundance pattern. We calculate a cross-correlation between mass changes and abundance changes to show how variations among the properties of participating nuclei may be explored. Our results provide further impetus for measurements of multiple quantities on individual short-lived neutron-rich isotopes at modern experimental facilities.

    Comments:
    10 pages, 8 figures; comments welcome
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2404.03699 [pdf]
    ApJ(2024)·7 citations
  3. 05

    [Submitted on 5 Apr 2024] (cross-list from hep-ph)

    Photo-production of near Threshold

    Wei-Yang Liu🇺🇸 · Ismail Zahed🇺🇸

    We analyze the photo-production of off a proton in the threshold region, in terms of C-odd gluonic correlations in the off-forward proton matrix element. Near threshold, the skewness is large leading to a production amplitude that is dominated by four C-odd twist-3 gluon GPDs. We use the QCD instanton vacuum to estimate these C-odd contributions in the proton. The results are used to estimate the differential cross sections for coherent photo-production of in the threshold region, at current electron facilities.

    Comments:
    25 pages, 9 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2404.03875 [pdf]
    PRD(2024)·9 citations
  4. 06

    [Submitted on 5 Apr 2024] (cross-list from astro-ph.HE)

    Maximal mass of the neutron star with a deconfined quark core

    Muhammed Shafeeque🇮🇳 · Arun Mathew🇮🇪 · Malay K. Nandy🇮🇳

    The nature of equation of state for the matter in the neutron star plays an important role in determining its maximal mass. In addition, it must comply with the condition of causality. Noting that the central density of a maximally massive neutron star is well above the nuclear saturation density, a deconfined quark core in the central region is motivated in this paper. We analyze this scenario by employing the MIT bag model to represent the core region and one of the unified equations of state for the region outside the core. Such combination is found to solve the problem of causality violation. In each case of the combined equations of state, the radial profile of displays a peak and dominant contribution to the total mass of the star comes from the region around the peak value of , whereas the contribution is small from the regions near the center and the surface. This peak occurs in the region of hadronic matter for the combinations considered in this paper. Importantly, we find that the position of the peak in is well-correlated with the maximal mass -- the highest value of obtains for the case with the peak occurring farthest from the center. This gravitational threshold being obtained for a non-rotating neutron star, we expect the threshold to lie well above 2 for a rapidly rotating neutron star, that may explain the existance of massive pulsars from recent astronomical observations.

    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2404.04009 [pdf]
    J.Astrophys.Astron.(2023)·3 citations
  5. 07

    [Submitted on 5 Apr 2024] (cross-list from astro-ph.HE)

    Unified equations of state for cold nonaccreting neutron stars with Brussels-Montreal functionals. V. Improved parametrization of the nucleon density distributions

    N.N. Shchechilin · N. Chamel · J.M. Pearson · A.I. Chugunov · A.Y. Potekhin

    We previously studied the inner crust and the pasta mantle of a neutron star within the 4th-order extended Thomas-Fermi (ETF) approach with consistent proton shell corrections added perturbatively via the Strutinsky integral (SI) theorem together with the contribution due to pairing. To speed up the computations and avoid numerical problems, we adopted parametrized nucleon density distributions. However, the errors incurred by the choice of the parametrization are expected to become more significant as the mean baryon number density is increased, especially in the pasta mantle where the differences in the energy per nucleon of the different phases are very small, typically a few keV. To improve the description of these exotic structures, we discuss the important features that a nuclear profile should fulfill and introduce two new parametrizations. Performing calculations using the BSk24 functional, we find that these parametrizations lead to lower ETF energy solutions for all pasta phases than the parametrization we adopted before and more accurately reproduce the exact equilibrium nucleon density distributions obtained from unconstrained variational calculations. Within the ETFSI method, all parametrizations predict the same composition in the region with quasi-spherical clusters. However, the two new parametrizations lead to a different mantle structure at mean baryon densities above about 0.07 fm^-3, at which point lasagna is energetically favored. Interestingly, spherical clusters reappear in the pasta region. The inverted pasta phases such as bucatini and Swiss cheese are still found in the densest region above the core in all cases.

    Comments:
    12 pages, 9 figures, published in Phys. Rev. C
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2404.04020 [pdf]
    PRC(2024)·18 citations
  6. 08

    [Submitted on 5 Apr 2024] (cross-list from hep-ph)

    Strangeness light multiquark baryons

    Brenda B. Malabarba🇧🇷 · K. P. Khemchandani🇰🇷 · A. Martinez Torres🇧🇷 · Seung-il Nam🇰🇷

    In view of the renewing experimental interest for searching strangeness baryons at J-PARC, we study the existence of light baryon resonances with strangeness +1 generated in the - system, where represents either //, and corresponds to . The description of the properties of the aforementioned states requires considering the dynamics involved in the coupled pseudoscalar-baryon and vector-baryon systems with strangeness in the s-wave. For the purpose of our current study, we consider the pseudoscalar-baryon (PB) and vector-baryon channels (VB) to which the mentioned and resonances couple and solve the Faddeev equations for the coupled channel system -, -, with all interactions being in the s-wave. Despite some strong attraction present in two of the subsystems, we do not find clear evidence supporting the formation of strangeness +1 states, with spin-parity , in the energy region MeV. However, the case of spin-parity seems more promising, showing the formation of a resonance with a mass around 2167 MeV, with a width of 90-100 MeV. We suggest that a signal of such a state could be found in processes with final states like , .

    Comments:
    New version: includes appendices with details on the formalisms used
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2404.04078 [pdf]
    PRD(2025)·8 citations
  7. 09

    [Submitted on 5 Apr 2024] (cross-list from hep-ph)

    Jet angularities in dijet production in proton-proton and heavy-ion collisions at RHIC

    Yang-Ting Chien🇺🇸 · Oleh Fedkevych🇺🇸 · Daniel Reichelt🇬🇧 · Steffen Schumann🇩🇪

    We study jet angularities for dijet production at the Relativistic Heavy Ion Collider (RHIC) in proton-proton (pp) and nucleus-nucleus (AA) collisions at 200 GeV nucleon-nucleon center-of-mass collision energy. In particular, we provide resummed predictions for angularity observables of groomed and ungroomed jets produced in collisions matched to next-to-leading order QCD calculations resulting in accuracy. Our parton-level predictions are corrected for non-perturbative effects, such as hadronization and underlying event, using parton-to-hadron level transfer matrices obtained with the Sherpa event generator. Furthermore, we use the Q-Pythia and JEWEL generators to estimate the impact of the interaction between quarks and gluons produced by the parton shower with the dense medium formed in heavy-ion collisions on the considered jet angularities.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2404.04168 [pdf]
    JHEP(2024)·18 citations

Affiliations

first authorsco-authorsvia INSPIRE