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Nuclear Theory·nucl-th

Thursday·May 2, 2024

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 05

    [Submitted on 30 Apr 2024] (cross-list from hep-ph)

    Does the Electron EDM Preclude Electroweak Baryogenesis ?

    Yuan-Zhen Li🇨🇳 · Michael J. Ramsey-Musolf🇨🇳 · Jiang-Hao Yu🇨🇳

    Electroweak baryogenesis (EWBG) constitutes a theoretically compelling and experimentally testable mechanism for explaining the origin of the baryon asymmetry of the universe (BAU). New results for the electric dipole moment (EDM) of the electron place significant constraints on the beyond Standard Model CP-violation needed for successful EWBG. Using a specific model illustration, we show how new developments in EWBG quantum transport theory that include CP-violating sources first order in gradients imply more relaxed EDM constraints -- and thereby greater EWBG viability -- than implied by previous approximation formulations. We also illustrate how these developments enable a more realistic treatment of CP-conserving interactions that can also have a decisive impact on the predicted BAU.

    Comments:
    6 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2404.19197 [pdf]
    Phys.Lett.B 140503 (2026)·11 citations
  2. 06

    [Submitted on 30 Apr 2024] (cross-list from astro-ph.HE)

    Role of local anisotropy in hybrid stars

    Luiz L. Lopes🇧🇷 · H. C. Das🇮🇳

    Using the Bower-Liang model, we discuss how pressure anisotropies affect the microscopic and macroscopic properties of hybrid stars. We find that anisotropies affect the maximum mass, central density, and radius of the canonical stars. Anisotropies also affect the minimum neutron star mass that presents quarks in their core, as well as the total amount of quarks for the maximally massive stars. We also confront our results with standard constraints, such as the radius and the tidal parameter of the canonical star, as well as the mass and radius of the PSR J0740+6620 pulsar. We observe that moderate values for anisotropies could fulfill these constraints simultaneously. On the other hand, within more extreme degrees of anisotropies, more speculative constraints such as black widow pulsars PSR J0952-0607 and the mass-gap object in the GW190814 event can be explained as hybrid stars. We also investigate the role of anisotropies in the neutron stars' moment of inertia.

    Comments:
    12 pages + Appendix
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2405.00072 [pdf]
    EPJC(2024)·7 citations
  3. 07

    [Submitted on 30 Apr 2024] (cross-list from hep-ph)

    Mass from Nothing

    Paul Romatschke🇺🇸 · Chun-Wei Su🇺🇸 · Ryan Weller🇺🇸

    We study the Abelian Higgs model with multiple scalar fields, but without mass terms. Solving the model non-perturbatively order-by-order in the number of scalar fields, we find that radiative corrections generate masses for the scalar and gauge boson, without spontaneous symmetry breaking. The mass scales are set by the -parameter of the electroweak running coupling, thereby naturally avoiding the hierarchy problem. No part of our calculation employs a weak-coupling expansion, and we find that the perturbative vacuum is metastable, and hence must decay to the stable non-perturbative vacuum of the theory, which we identify. Although the field content of our Lagrangian is standard, our results predict the existence of two heavy scalar resonances in addition to the Higgs. We believe that these predicted resonances will ultimately allow experimentalists to discriminate between our method and standard solutions of the Higgs model.

    Comments:
    25 pages, no figures; v2: updated references, clarified setup; comments, criticisms and citation requests still welcome!
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2405.00088 [pdf]
    PRD(2024)·10 citations
  4. 08

    [Submitted on 1 May 2024] (cross-list from hep-ph)

    A first-order deconfinement phase transition in the early universe and gravitational waves

    Fei Gao🇨🇳 · Sichun Sun🇨🇳 · Graham White🇬🇧

    We clarify the conditions of the cosmic quantum chromodynamics (QCD) first-order phase transition in the early universe by carefully distinguishing the chiral and deconfinement phase transitions. While the chiral one with light quarks at zero chemical potential is unlikely to be first order based on the recent lattice QCD calculations, the latter one can be naturally extended with one extra rolling scalar to be first order. The argument is also valid for the dark QCD theory with arbitrary with a wide range of phase transition temperatures, which can be from hundreds of MeV up to beyond TeV. Notably, here we derive the general formula for the deconfinement phase transition potential of SU() gauge theory characterized by the Polyakov loop. With the effective potential in hand, the gravitational wave spectrum is then determined via the sound shell model, which then enables us to give for the first time the quantitative analysis of the gravitational wave signals coming from the QCD deconfinement phase transition and awaits the check from future space interferometers.

    Comments:
    6 pages, 2 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2405.00490 [pdf]
    6 citations

Affiliations

first authorsco-authorsvia INSPIRE