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Nuclear Theory·nucl-th

Monday·January 25, 2021

4 papers—1 primary·3 cross-listed

All4Primary1Cross-lists3
  1. 01

    [Submitted on 22 Jan 2021]

    Transport properties of superfluid phonons in neutron stars

    Cristina Manuel🇪🇸 · Laura Tolos🇪🇸

    We review the effective field theory associated with the superfluid phonons that we use for the study of transport properties in the core of superfluid neutrons stars in their low temperature regime. We then discuss the shear and bulk viscosities together with the thermal conductivity coming from the collisions of superfluid phonons in neutron stars. With regard to shear, bulk, and thermal transport coefficients, the phonon collisional processes are obtained in terms of the equation of state and the superfluid gap. We compare the shear coefficient due to the interaction among superfluid phonons with other dominant processes in neutron stars, such as electron collisions. We also analyze the possible consequences for the r-mode instability in neutron stars. As for the bulk viscosities, we determine that phonon collisions contribute decisively to the bulk viscosities inside neutron stars. For the thermal conductivity resulting from phonon collisions, we find that it is temperature independent well below the transition temperature. We also obtain that the thermal conductivity due to superfluid phonons dominates over the one resulting from electron-muon interactions once phonons are in the hydrodynamic regime. As the phonons couple to the electroweak gauge boson, we estimate the associated neutrino emissivity. We also briefly comment on how the superfluid phonon interactions are modified in the presence of a gravitational field or in a moving background.

    Comments:
    23 pages, 9 figures, invited short review for the Special Issue 'Superfluidity and Superconductivity in Neutron Stars' of Universe MDPI Journal
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2101.09000 [pdf]
    Universe(2021)·3 citations
  2. 02

    [Submitted on 22 Jan 2021] (cross-list from hep-ph)

    Photoproduction in an effective Lagrangian approach

    Neng-Chang Wei🇨🇳 · Yu Zhang🇨🇳 · Fei Huang🇨🇳 · De-Min Li🇨🇳

    The data on differential cross sections and photon-beam asymmetries for the reaction have been analyzed within a tree-level effective Lagrangian approach. In addition to the -channel and exchanges, the -channel exchange, the -channel nucleon exchange, and the interaction current, a minimal number of nucleon resonances in the channel are introduced in constructing the reaction amplitudes to describe the data. The results show that the experimental data can be well reproduced by including either the or the resonance. In both cases, the contact term and the exchange are found to make significant contributions, while the contributions from the and exchanges are negligible in the former case and considerable in the latter case. Measurements of the data on target asymmetries are called on to further pin down the resonance contents and to clarify the roles of the and exchanges in this reaction.

    Comments:
    12 pages, 8 figures; version published in Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2101.08988 [pdf]
    PRD(2021)·12 citations
  3. 03

    [Submitted on 22 Jan 2021] (cross-list from hep-ph)

    Deconfining Phase Boundary of Rapidly Rotating Hot and Dense Matter and Analysis of Moment of Inertia

    Yuki Fujimoto🇯🇵 · Kenji Fukushima🇯🇵 · Yoshimasa Hidaka🇯🇵

    We discuss the effect of rapid rotation on the phase diagram of hadronic matter. The energy dispersion relation is shifted by an effective chemical potential induced by rotation. This suggests that rotation should lower the critical temperature of chiral restoration, but it is still controversial how the deconfinement temperature should change as a function of angular velocity. We adopt the hadron resonance gas model as an approach free from fitting parameters. We identify the deconfinement from the thermodynamic behavior and find that rotation decreases the deconfinement temperature. We also discuss the spatial inhomogeneity of the pressure and give a semi-quantitative estimate of the moment of inertia.

    Comments:
    7 pages, 3 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2101.09173 [pdf]
    PLB(2021)·109 citations
  4. 04

    [Submitted on 22 Jan 2021] (cross-list from nucl-ex)

    QCD Critical Point and High Baryon Density Matter

    Bedangadas Mohanty🇮🇳 · Nu Xu🇨🇳

    We report the latest results on the search for the QCD critical point in the QCD phase diagram through high energy heavy-ion collisions. The measurements discussed are based on the higher moments of the net-proton multiplicity distributions in heavy-ion collisions. A non-monotonic variation in the product of kurtosis times the variance of the net-proton distribution is observed as a function of the collision energy with 3 significance. We also discuss the results of the thermal model in explaining the measured particle yield ratios in heavy-ion collisions and comparison of the different variants of hardon resonance gas model calculation to the data on higher moments of net-proton distributions. We end with a note that the upcoming programs in high baryon density regime at various experimental facilities will complete the search for the QCD critical point through heavy-ion collisions.

    Comments:
    10 pages, 6 figures and Presented at workshop on "Criticality in QCD and the Hadron Resonance Gas", Wroclaw (online), July 29-31, 2020. arXiv admin note: text overlap with arXiv:2009.03006
    Subjects:
    Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2101.09210 [pdf]
    Acta Phys.Polon.Supp.(2021)·4 citations

Affiliations

first authorsco-authorsvia INSPIRE