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Nuclear Theory·nucl-th

Thursday·August 1, 2024

11 papers—5 primary·6 cross-listed

All11Primary5Cross-lists6
  1. 01

    [Submitted on 30 Jul 2024]

    Determination of electron screening potential of 6 Li(p,{\alpha})3 He reaction using MultiLayer Perceptron based neural network

    D. Chattopadhyay

    Background: Understanding the nuclear reactions between light charged nuclei at sub-coulomb energy region holds significant importance in several astrophysical processes. Determination of the precise reaction cross-section within the astrophysically important Gamow range is difficult because of electron screening. Various polynomial fits, R-Matrix and Indirect Trojan horse method estimate much higher electron screening energies as compared to the adiabatic limit. Purpose: Obtain the bare astrophysical S-factor of 6 Li(p,{\alpha})3 He using Multi-Layer Perceptron based Artificial Neural Network based analysis and extract the electron screening energies. Methods: Experimental S-factor of 6 Li(p,{\alpha})3 He, available in literature, are reanalyzed using the Multi-LayerPerceptron based Artificial Neural Network based algorithm to obtain the energy dependent astrophysical S-factor. Bare astrophysical S-factor is also calculated using the same Feed-forward Artificial Neural Network from the data range above 60 keV where the electron screening effect is expected to be negligible. Electron screening potential is then obtained by taking the ratio of total shielded S-factor with the bare S-factor. Results and Conclusions: The electron screening potential obtained from the Present work through the Artificial Neural network based algorithm is found to be 220 eV. The extracted electron screening potential through the present analysis indicates that the Artificial Neural Network might be an alternative tools for estimation the electron screening potential involving light nuclei.

    Comments:
    arXiv admin note: substantial text overlap with arXiv:2407.20049
    Subjects:
    Nuclear Theory (nucl-th); Instrumentation and Methods for Astrophysics (astro-ph.IM)
    arXiv:
    2407.21089 [pdf]
    Nucl.Instrum.Meth.B(2024)·2 citations
  2. 02

    [Submitted on 30 Jul 2024]

    Investigating the crust of neutron stars with neural-network quantum states

    Bryce Fore · Jane Kim · Morten Hjorth-Jensen · Alessandro Lovato

    An accurate description of low-density nuclear matter is crucial for explaining the physics of neutron star crusts. In the density range between approximately 0.01 fm and 0.1 fm, matter transitions from neutron-rich nuclei to various higher-density pasta shapes, before ultimately reaching a uniform liquid. In this work, we introduce a variational Monte Carlo method based on a neural Pfaffian-Jastrow quantum state, which allows us to model the transition from the liquid phase to neutron-rich nuclei microscopically. At low densities, nuclear clusters dynamically emerge from the microscopic interactions among protons and neutrons, which we model based on pionless effective field theory. Our variational Monte Carlo approach represents a significant improvement over the state-of-the-art auxiliary-field diffusion Monte Carlo method, which is severely hindered by the fermion-sign problem in this low-density regime and cannot capture the onset of clusters. In addition to computing the energy per particle of symmetric nuclear matter and pure neutron matter, we analyze an intermediate isospin-asymmetry configuration to elucidate the formation of nuclear clusters. We also provide evidence that the presence of such nuclear clusters influences the amount of protons in the crust compared to protons in beta-equilibrated, neutrino-transparent matter.

    Comments:
    10 pages, 5 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
    arXiv:
    2407.21207 [pdf]
    Commun.Phys.(2025)·16 citations
  3. 03

    [Submitted on 31 Jul 2024]

    Considerations on measuring spin-spin correlation of hyeprons in heavy-ion experiments

    Diyu Shen🇨🇳 · Jinhui Chen🇨🇳 · Aihong Tang🇺🇸

    The significant global spin alignment observed for mesons in heavy-ion collisions has sparked intense discussions about its origin and implications. One explanation suggests that fluctuations in the strong force field may introduce strong spin correlations between strange () and anti-strange () quarks, leading to the global spin alignment of mesons. Extending this line of research, the theoretical community has proposed studying the spin correlation between and hyperons. In this paper, we construct experimental observables and make connections between them and the theoretical proposed quantities.

    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex)
    arXiv:
    2407.21291 [pdf]
    7 citations
  4. 04

    [Submitted on 31 Jul 2024]

    Neutrino and antineutrino charged-current multi-nucleon cross sections revisited

    J. E. Sobczyk🇩🇪 · J. Nieves🇪🇸

    In this work we improve on several aspects of the computation of the (anti-)neutrino charged-current multi-nucleon cross section carried out in Phys.Rev.C 83 (2011) 045501 and Phys.Rev.C 102 (2020) 024601. Most importantly, we implement a consistent treatment of the nucleon self-energy in the amplitude entering the definition of the two-particle two-hole (2p2h) cross-section, and estimate the source of uncertainty of our model due to a simplified treatment of the self-energy. Our new predictions are around higher than previously. We show comparisons for the inclusive lepton double-differential cross sections, with no pions in the final state, measured by MiniBooNE on carbon and by T2K on carbon and oxygen. In all cases, we find an excellent reproduction of the experiments, and in particular, the neutrino MiniBooNE data is now well described without requiring a global re-scaling of the flux. In addition, we take the opportunity of this revision to discuss in detail several important issues of the calculation of the 2p2h cross section, delving into the microscopic dynamics of the multi-nucleon mechanisms. The improved treatment presented in this work provides realistic first-step emitted two-nucleon final state momentum configurations, beyond the approximation of phase-space distributions.

    Comments:
    16 pages, 9 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2407.21587 [pdf]
    PRC(2025)·11 citations
  5. 05

    [Submitted on 31 Jul 2024]

    Weak rates in strongly coupled cold quark matter

    Carlos Hoyos🇪🇸 · Andrea Olzi🇮🇹 · David Rodriguez-Fernandez🇪🇸

    The rates of flavor-changing weak processes are crucial in determining the conditions of beta equilibrium in neutron stars and mergers, influencing the damping of oscillations, the stability of rotating pulsars, and the emission of gravitational waves. We derive a formula for these rates at nonzero temperature, to leading order in the Fermi coupling and exact in the QCD coupling. Utilizing a simple phenomenological holographic model dual to QCD, we study massless unpaired quark matter at high densities. We numerically compute the rate for small deviations from beta equilibrium and derive an analytic approximation for small temperatures. Our findings reveal that, compared to the perturbative result, the rate is suppressed by logarithmic factors of the temperature.

    Comments:
    20 pages+appendices, 5 figures, minor corrections
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
    arXiv:
    2407.21643 [pdf]
    JHEP(2024)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE