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Nuclear Theory·nucl-th

Thursday·November 5, 2020

7 papers—2 primary·5 cross-listed

All7Primary2Cross-lists5
  1. 03

    [Submitted on 3 Nov 2020] (cross-list from astro-ph.HE)

    New Developments in Flavor Evolution of a Dense Neutrino Gas

    Irene Tamborra🇩🇰 · Shashank Shalgar (Niels Bohr Institute)🇩🇰

    Neutrino-neutrino refraction dominates the flavor evolution in core-collapse supernovae, neutron-star mergers, and the early universe. Ordinary neutrino flavor conversion develops on timescales determined by the vacuum oscillation frequency. However, when the neutrino density is large enough, collective flavor conversion may arise because of pairwise neutrino scattering. Pairwise conversion is deemed to be fast as it is expected to occur on timescales that depend on the neutrino-neutrino interaction energy (i.e., on the neutrino number density) and is regulated by the angular distributions of electron neutrinos and antineutrinos. The enigmatic phenomenon of fast pairwise conversion has been overlooked for a long time. However, because of the fast conversion rate, pairwise conversion may possibly occur in the proximity of the neutrino decoupling region with yet to be understood implications for the hydrodynamics of astrophysical sources and the synthesis of the heavy elements. We review the physics of this fascinating phenomenon and its implications for neutrino-dense sources.

    Comments:
    25 pages, including 7 figures; to appear in Annual Review of Nuclear and Particle Science, vol. 71. Preprint matching the version accepted for publication
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.01948 [pdf]
    Ann.Rev.Nucl.Part.Sci.(2021)·249 citations
  2. 04

    [Submitted on 4 Nov 2020] (cross-list from cond-mat.quant-gas)

    Constrained extrapolation problem and order-dependent mappings

    Corbinian Wellenhofer🇩🇪 · Daniel R. Phillips🇺🇸 · Achim Schwenk🇩🇪

    We consider the problem of extrapolating the perturbation series for the dilute Fermi gas in three dimensions to the unitary limit of infinite scattering length and into the BEC region, using the available strong-coupling information to constrain the extrapolation problem. In this constrained extrapolation problem (CEP) the goal is to find classes of approximants that give well converged results already for low perturbative truncation orders. First, we show that standard Padé and Borel methods are too restrictive to give satisfactory results for this CEP. A generalization of Borel extrapolation is given by the so-called Maximum Entropy extrapolation method (MaxEnt). However, we show that MaxEnt requires extensive elaborations to be applicable to the dilute Fermi gas and is thus not practical for the CEP in this case. Instead, we propose order-dependent-mapping extrapolation (ODME) as a simple, practical, and general method for the CEP. We find that the ODME approximants for the ground-state energy of the dilute Fermi gas are robust with respect to changes of the mapping choice and agree with results from quantum Monte Carlo simulations within uncertainties.

    Comments:
    19 pages, 3 figures. Paper prepared for the Festschrift in honor of the 60th birthday of Prof. D.A. Drabold. This version has minor changes in response to referee comments. Almost identical to version published in Physica Status Solidi B: Basic Solid State Physics
    Subjects:
    Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.02105 [pdf]
    Phys.Status Solidi B(2021)·4 citations
  3. 05

    [Submitted on 4 Nov 2020] (cross-list from hep-ph)

    Critical exponents and transport properties near the QCD critical endpoint from the statistical bootstrap model

    Guruprasad Kadam🇮🇳 · Hiranmaya Mishra🇮🇳 · Marco Panero🇮🇹

    We present an estimate of the behaviour of the shear and bulk viscosity coefficients when the QCD critical point is approached from the hadronic side, describing hadronic matter within the statistical bootstrap model (SBM) of strong interactions. The boostrap model shows critical behavior near the quark-hadron transition temperature if the parameter characterizing the degeneracy of Hagedorn states is properly chosen. We calculate the critical exponents and amplitudes of relevant thermodynamic quantities near the QCD critical point and combine them with an Ansatz for the shear and bulk viscosity coefficients to derive the behavior of these coefficients near the critical point. The shear viscosity to entropy density ratio is found to decrease when the temperature is increased, and to approach the Kovtun-Son-Starinets bound 1/(4{\pi}) faster near the critical point, while the bulk viscosity coefficient is found to rise very rapidly.

    Comments:
    21 pages, 6 figures. Published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.02171 [pdf]
    EPJC(2021)·7 citations
  4. 06

    [Submitted on 4 Nov 2020] (cross-list from astro-ph.HE)

    Effect of hyperons on f-mode oscillations in Neutron Stars

    Bikram Keshari Pradhan🇮🇳 · Debarati Chatterjee🇮🇳

    As the densities in the interior of neutron stars exceed those of terrestrial nuclear experiments, they provide a scope for studying the nature of dense matter under extreme conditions. The composition of the inner core of neutron stars is highly uncertain, and it is speculated that exotic forms of matter such as hyperons may appear there. Gravitational waves emitted by unstable oscillation modes in neutron stars contain information about their interior composition and therefore allow us to probe the interior directly. Recently, a systematic investigation of f-mode oscillations in neutron stars revealed the role of the uncertainty in nuclear saturation parameters, particularly the effective nucleon mass, on its frequency. In this work, we study the influence of the appearance of hyperons on f-mode oscillation frequencies and therefore on the emission of gravitational waves. We also speculate whether a future detection of f-mode frequencies could provide a possibility of probing the presence of hyperons in the neutron star core.

    Comments:
    14 pages, 16 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    2011.02204 [pdf]
    PRC(2021)·63 citations
  5. 07

    [Submitted on 4 Nov 2020] (cross-list from hep-ph)

    Gluon imaging using azimuthal correlations in diffractive scattering at the Electron-Ion Collider

    Heikki Mäntysaari🇫🇮 · Kaushik Roy🇩🇪 · Farid Salazar🇺🇸 · Björn Schenke🇺🇸

    We study coherent diffractive photon and vector meson production in electron-proton and electron-nucleus collisions within the Color Glass Condensate effective field theory. We show that electron-photon and electron-vector meson azimuthal angle correlations are sensitive to non-trivial spatial correlations in the gluon distribution of the target, and perform explicit calculations using spatially dependent McLerran-Venugopalan initial color charge configurations coupled to the numerical solution of small JIMWLK evolution equations. We compute the cross-section differentially in and and find sizeable anisotropies in the electron-photon and electron- azimuthal correlations () in electron-proton collisions for the kinematics of the future Electron-Ion Collider. In electron-gold collisions these modulations are found to be significantly smaller (). We also compute incoherent diffractive production where we find that the azimuthal correlations are sensitive to fluctuations of the gluon distribution in the target.

    Comments:
    32 figures, 18 figures. v2: corrected typos in Eqs. 21 and 36, figures updated accordingly
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2011.02464 [pdf]
    PRD(2021)·73 citations

Affiliations

first authorsco-authorsvia INSPIRE