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Nuclear Theory·nucl-th

Friday·March 5, 2021

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 03

    [Submitted on 3 Mar 2021] (cross-list from astro-ph.HE)

    Neutrino Fast Flavor Conversions in Neutron-star Post-Merger Accretion Disks

    Xinyu Li🇨🇦 · Daniel M. Siegel🇨🇦

    A compact accretion disk may be formed in the merger of two neutron stars or of a neutron star and a stellar-mass black hole. Outflows from such accretion disks have been identified as a major site of rapid neutron-capture (r-process) nucleosynthesis and as the source of 'red' kilonova emission following the first observed neutron-star merger GW170817. We present long-term general-relativistic radiation magnetohydrodynamic simulations of a typical post-merger accretion disk at initial accretion rates of over 400ms post-merger. We include neutrino radiation transport that accounts for effects of neutrino fast flavor conversions dynamically. We find ubiquitous flavor oscillations that result in a significantly more neutron-rich outflow, providing lanthanide and 3rd-peak r-process abundances similar to solar abundances. This provides strong evidence that post-merger accretion disks are a major production site of heavy r-process elements. A similar flavor effect may allow for increased lanthanide production in collapsars. The formalism presented here may also be used in simulations of core-collapse supernovae to explore whether fast conversions strengthen or weaken the explosion.

    Comments:
    7 pages, 3 figures, Accepted for publication in PRL
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2103.02616 [pdf]
    PRL(2021)·132 citations
  2. 04

    [Submitted on 4 Mar 2021] (cross-list from hep-ph)

    Nucleon mass radii and distribution: Holographic QCD, Lattice QCD and GlueX data

    Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸

    We briefly review and expand our recent analysis for all three invariant A,B,D gravitational form factors of the nucleon in holographic QCD. They compare well to the gluonic gravitational form factors recently measured using lattice QCD simulations. The holographic A-term is fixed by the tensor (graviton) Regge trajectory, and the D-term by the difference between the tensor (graviton) and scalar (dilaton) Regge trajectories. The B-term is null in the absence of a tensor coupling to a Dirac fermion in bulk. A first measurement of the tensor form factor A-term is already accessible using the current GlueX data, and therefore the tensor gluonic mass radius, pressure and shear inside the proton, thanks to holography. The holographic A-term and D-term can be expressed exactly in terms of harmonic numbers. The tensor mass radius from the holographic threshold is found to be , in agreement with as extracted from the overall numerical lattice data, and empirical GlueX data. The scalar mass radius is found to be slightly larger .

    Comments:
    16 pages, 4 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2103.03186 [pdf]
    PRD(2021)·85 citations

Affiliations

first authorsco-authorsvia INSPIRE