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Nuclear Theory·nucl-th

Friday·October 13, 2023

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 03

    [Submitted on 11 Oct 2023] (cross-list from hep-ph)

    Light quark mass dependence of nucleon electromagnetic form factors in dispersively modified chiral perturbation theory

    Fernando Alvarado🇪🇸 · Di An🇸🇪 · Luis Alvarez-Ruso🇪🇸 · Stefan Leupold🇸🇪

    The nucleon isovector electromagnetic form factors are calculated up to next-to-next-to-leading order by combining relativistic chiral perturbation theory (ChPT) of pion, nucleon, and (1232) with dispersion theory. We specifically address the light-quark mass dependence of the form factors, achieving a good description of recent Lattice QCD results over a range of GeV and MeV. For the Dirac form factor, the combination of ChPT and dispersion theory outperforms the pure dispersive and pure ChPT descriptions. For the Pauli form factor, the combined calculation leads to results comparable to the purely dispersive ones. The anomalous magnetic moment and the Dirac and Pauli radii are extracted.

    Comments:
    27 pages, 13 figures. It contains supplementary material "anc"
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2310.07796 [pdf]
    PRD(2023)·12 citations
  2. 04

    [Submitted on 12 Oct 2023] (cross-list from hep-lat)

    Lattice real-time simulations with learned optimal kernels

    Daniel Alvestad🇳🇴 · Alexander Rothkopf🇳🇴 · Dénes Sexty🇦🇹

    We present a simulation strategy for the real-time dynamics of quantum fields, inspired by reinforcement learning. It builds on the complex Langevin approach, which it amends with system specific prior information, a necessary prerequisite to overcome this exceptionally severe sign problem. The optimization process underlying our machine learning approach is made possible by deploying inherently stable solvers of the complex Langevin stochastic process and a novel optimality criterion derived from insight into so-called boundary terms. This conceptual and technical progress allows us to both significantly extend the range of real-time simulations in 1+1d scalar field theory beyond the state-of-the-art and to avoid discretization artifacts that plagued previous real-time field theory simulations. Limitations of and promising future directions are discussed.

    Comments:
    5 pages, 5 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); cond-mat.other (cond-mat.other); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Machine Learning (stat.ML)
    arXiv:
    2310.08053 [pdf]
    PRD(2024)·26 citations
  3. 05

    [Submitted on 12 Oct 2023] (cross-list from hep-lat)

    Gravitational form factors of the proton from lattice QCD

    Daniel C. Hackett🇺🇸 · Dimitra A. Pefkou🇺🇸 · Phiala E. Shanahan🇺🇸

    The gravitational form factors (GFFs) of a hadron encode fundamental aspects of its structure, including its shape and size as defined from e.g., its energy density. This work presents a determination of the flavor decomposition of the GFFs of the proton from lattice QCD, in the kinematic region . The decomposition into up-, down-, strange-quark, and gluon contributions provides first-principles constraints on the role of each constituent in generating key proton structure observables, such as its mechanical radius, mass radius, and -term.

    Comments:
    Version published in PRL
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2310.08484 [pdf]
    PRL(2024)·154 citations

Affiliations

first authorsco-authorsvia INSPIRE