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Nuclear Theory·nucl-th

Wednesday·April 8, 2020

12 papers—8 primary·4 cross-listed

All12Primary8Cross-lists4
  1. 09

    [Submitted on 7 Apr 2020] (cross-list from hep-ph)

    Model Independent Extraction of the Proton Charge Radius from PRad data

    Gil Paz🇺🇸

    The proton radius puzzle has motivated several new experiments that aim to extract the proton charge radius and resolve the puzzle. Recently PRad, a new electron-proton scattering experiment at Jefferson Lab, reported a proton charge radius of . The value was obtained by using a rational function model for the proton electric form factor. We perform a model-independent extraction using -expansion of the proton charge radius from PRad data. We find that the model-independent statistical error is more than 50\% larger compared to the statistical error reported by PRad.

    Comments:
    11 pages, 4 figures, references added, journal version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2004.03077 [pdf]
    Mod.Phys.Lett.A(2021)·7 citations
  2. 10

    [Submitted on 7 Apr 2020] (cross-list from hep-ph)

    Heavy quarkonia in a bulk viscous medium

    Lata Thakur🇰🇷 · Najmul Haque🇮🇳 · Yuji Hirono🇰🇷

    We study the properties of heavy quarkonia in a quark-gluon plasma in the presence of bulk viscous effects. Within the hard thermal loop approximation at one-loop, the dielectric permittivity of quark-gluon plasma is computed, where the bulk viscous effect enters through the deformation of the distribution functions of thermal quarks and gluons. Based on the modified dielectric permittivity, we compute the in-medium heavy quark potential, that includes non-pertubative string-like terms as well as the perturbative Coulombic term. We discuss how the bulk viscous effect modifies the real and imaginary parts of the in-medium potential. Several prescriptions are examined as to how to include the string-like non-perturbative potentials. Using the deformed potential, we compute the wave functions, binding energies, and decay widths of heavy quarkonia in a bulk viscous medium, and study their sensitivity to the strength of the bulk viscous effect. An estimate of the melting temperatures is given.

    Comments:
    29 pages, 13 figures, v2, published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2004.03426 [pdf]
    JHEP(2020)·31 citations
  3. 11

    [Submitted on 7 Apr 2020] (cross-list from hep-ph)

    Large-Momentum Effective Theory

    Xiangdong Ji🇺🇸 · Yu-Sheng Liu🇨🇳 · Yizhuang Liu🇨🇳 · Jian-Hui Zhang🇨🇳 · Yong Zhao🇺🇸

    Since the parton model was introduced by Feynman more than fifty years ago, we have learned much about the partonic structure of the proton through a large body of high-energy experimental data and dedicated global fits. However, calculating the partonic observables such as parton distribution function (PDFs) from the fundamental theory of strong interactions, QCD, has made limited progress. Recently, the authors have advocated a formalism, large-momentum effective theory (LaMET), through which one can extract parton physics from the properties of the proton travelling at a moderate boost-factor, e.g., . The key observation behind this approach is that Lorentz symmetry allows the standard formalism of partons in terms of light-front operators to be replaced by an equivalent one with large-momentum states and time-independent operators of a universality class. With LaMET, the PDFs, generalized PDFs or GPDs, transverse-momentum-dependent PDFs, and light-front wave functions can all be extracted in principle from lattice simulations of QCD (or other non-perturbative methods) through standard effective field theory matching and running. Future lattice QCD calculations with exa-scale computational facilities can help to understand the experimental data related to the hadronic structure, including those from the upcoming Electron-Ion Colliders dedicated to exploring the partonic landscape of the proton. Here we review the progress made in the past few years in development of the LaMET formalism and its applications, particularly on the demonstration of its effectiveness from initial lattice QCD simulations.

    Comments:
    75 pages, 23 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2004.03543 [pdf]
    RMP(2021)·382 citations
  4. 12

    [Submitted on 7 Apr 2020] (cross-list from hep-ph)

    Non-perturbative renormalization scheme for the CP-odd three-gluon operator

    Vincenzo Cirigliano🇺🇸 · Emanuele Mereghetti🇺🇸 · Peter Stoffer🇺🇸

    We define a regularization-independent momentum-subtraction scheme for the -odd three-gluon operator at dimension six. This operator appears in effective field theories for heavy physics beyond the Standard Model, describing the indirect effect of new sources of -violation at low energies. In a hadronic context, it induces permanent electric dipole moments. The hadronic matrix elements of the three-gluon operator are non-perturbative objects that should ideally be evaluated with lattice QCD. We define a non-perturbative renormalization scheme that can be implemented on the lattice and we compute the scheme transformation to at one loop. Our calculation can be used as an interface to future lattice-QCD calculations of the matrix elements of the three-gluon operator, in order to obtain theoretically robust constraints on physics beyond the Standard Model from measurements of the neutron electric dipole moment.

    Comments:
    70 pages, 6 figures; version published in JHEP
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2004.03576 [pdf]
    JHEP(2020)·28 citations

Affiliations

first authorsco-authorsvia INSPIRE