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Nuclear Theory·nucl-th

Friday·August 20, 2021

8 papers—3 primary·5 cross-listed

All8Primary3Cross-lists5
  1. 04

    [Submitted on 18 Aug 2021] (cross-list from astro-ph.HE)

    Resolving the fastest ejecta from binary Neutron Star mergers: implications for electromagnetic counterparts

    Coleman Dean · Rodrigo Fernández · Brian D. Metzger

    We examine the effect of spatial resolution on initial mass ejection in grid-based hydrodynamic simulations of binary neutron star mergers. The subset of the dynamical ejecta with velocities greater than c can generate an ultraviolet precursor to the kilonova on hr timescales and contribute to a years-long non-thermal afterglow. Previous work has found differing amounts of this fast ejecta, by one- to two orders of magnitude, when using particle-based or grid-based hydrodynamic methods. Here we carry out a numerical experiment that models the merger as an axisymmetric collision in a co-rotating frame, accounting for Newtonian self-gravity, inertial forces, and gravitational wave losses. The lower computational cost allows us to reach spatial resolutions as high as m, or of the stellar radius. We find that fast ejecta production converges to within for a cell size of m. This suggests that fast ejecta quantities found in existing grid-based merger simulations are unlikely to increase to the level needed to match particle-based results upon further resolution increases. The resulting neutron-powered precursors are in principle detectable out to distances Mpc with upcoming facilities. We also find that head-on collisions at the free-fall speed, relevant for eccentric mergers, yield fast and slow ejecta quantities of order , with a kilonova signature distinct from that of quasi-circular mergers.

    Comments:
    Accepted by ApJ
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)
    arXiv:
    2108.08311 [pdf]
    ApJ(2021)·23 citations
  2. 05

    [Submitted on 19 Aug 2021] (cross-list from astro-ph.HE)

    Comparison of simulated neutrino emission models with data on Supernova 1987A

    Jackson Olsen🇺🇸 · Yong-Zhong Qian🇺🇸

    We compare models of supernova (SN) neutrino emission with the Kamiokande II data on SN 1987A using the Bayesian approach. These models are taken from simulations and are representative of current 1D SN models. We find that models with a brief accretion phase of neutrino emission are the most favored. This result is not affected by varying the overall flux normalization or considering neutrino oscillations. We also check the compatibility of the best-fit models with the data.

    Comments:
    7 pages, 5 figures
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2108.08463 [pdf]
    PRD(2021)·11 citations
  3. 06

    [Submitted on 19 Aug 2021] (cross-list from hep-lat)

    Local correlation among the chiral condensate, monopoles, and color magnetic fields in Abelian projected QCD

    Hideo Suganuma (Kyoto U.)🇯🇵 · Hiroki Ohata (YITP, Kyoto U.)🇯🇵

    Using the lattice gauge field theory, we study the relation among the local chiral condensate, monopoles, and color magnetic fields in quantum chromodynamics (QCD). First, we investigate idealized Abelian gauge systems of 1) a static monopole-antimonopole pair and 2) a magnetic flux without monopoles, on a four-dimensional Euclidean lattice. In these systems, we calculate the local chiral condensate on quasi-massless fermions coupled to the Abelian gauge field, and find that the chiral condensate is localized in the vicinity of the magnetic field. Second, using SU(3) lattice QCD Monte Carlo calculations, we investigate Abelian projected QCD in the maximally Abelian gauge, and find clear correlation of distribution similarity among the local chiral condensate, monopoles, and color magnetic fields in the Abelianized gauge configuration. As a statistical indicator, we measure the correlation coefficient , and find a strong positive correlation of between the local chiral condensate and an Euclidean color-magnetic quantity in Abelian projected QCD. The correlation is also investigated for the deconfined phase in thermal QCD. As an interesting conjecture, like magnetic catalysis, the chiral condensate is locally enhanced by the strong color-magnetic field around the monopoles in QCD.

    Comments:
    15 pages, 7 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2108.08499 [pdf]
    Universe(2021)·6 citations
  4. 07

    [Submitted on 19 Aug 2021] (cross-list from hep-ph)

    Transport properties and equation-of-state of hot and dense QGP matter near the critical end-point in the phenomenological dynamical quasi-particle model

    Olga Soloveva🇩🇪 · Jörg Aichelin🇫🇷 · Elena Bratkovskaya🇩🇪

    We extend the effective dynamical quasiparticle model (DQPM) - constructed for the description of non-perturbative QCD phenomena of the strongly interacting quark-gluon plasma (QGP) - to large baryon chemical potentials, , including a critical end-point and a 1st order phase transition. The DQPM description of quarks and gluons is based on partonic propagators with complex selfenergies where the real part of the selfenergies is related to the quasiparticle mass and the imaginary part to a finite width of their spectral functions. In DQPM the determination of complex selfenergies for the partonic degrees of freedom at zero and finite has been performed by adjusting the entropy density to the lQCD data. The temperature-dependent effective coupling (squared) , as well as the parton effective masses and widths are based on this adjustment. The novel extended dynamical quasiparticle model, named "DQPM-CP", makes it possible to describe thermodynamical and transport properties of quarks and gluons in a wide range of and , and reproduces the equation-of-state (EoS) of lQCD calculations in the crossover region of finite . We apply a scaling ansatz for the strong coupling constant near the CEP, located at (, GeV. We show the EoS as well as the speed of sound for and for a wide range of , which can be of interest for hydrodynamical simulations. Furthermore, we consider two settings for the strange quark chemical potentials (I) and (II) . The isentropic trajectories of the QGP matter are compared for these two cases. The phase diagram of DQPM-CP is close to PNJL calculations. The leading order pQCD transport coefficients of both approaches differ. This elucidates that the knowledge of the phase diagram alone is not sufficient to describe the dynamical evolution of QGP.

    Comments:
    18 pages, 17 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2108.08561 [pdf]
    PRD(2022)·32 citations
  5. 08

    [Submitted on 19 Aug 2021] (cross-list from hep-ph)

    Quantum information approach to high energy interactions

    Dmitri E. Kharzeev🇺🇸

    High energy hadron interactions are commonly described by using a probabilistic parton model that ignores quantum entanglement present in the light-cone wave functions. Here we argue that since a high energy interaction samples an instant snapshot of the hadron wave function, the phases of different Fock state wave functions cannot be measured - therefore the light-cone density matrix has to be traced over these unobservable phases. Performing this trace with the corresponding Haar integration measure leads to "Haar scrambling" of the density matrix, and to the emergence of entanglement entropy. This entanglement entropy is determined by the Fock state probability distribution, and is thus directly related to the parton structure functions. As proposed earlier, at large rapidity the hadron state becomes maximally entangled, and the entanglement entropy is according to QCD evolution equations. When the phases of Fock state components are controlled, for example in spin asymmetry measurements, the Haar average cannot be performed, and the probabilistic parton description breaks down.

    Comments:
    9 pages; one typo corrected for archiving purposes, no other changes
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2108.08792 [pdf]
    Phil.Trans.A.Math.Phys.Eng.Sci.(2021)·54 citations

Affiliations

first authorsco-authorsvia INSPIRE