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Nuclear Theory·nucl-th

Monday·March 1, 2021

9 papers—5 primary·4 cross-listed

All9Primary5Cross-lists4
  1. 06

    [Submitted on 25 Feb 2021] (cross-list from hep-ph)

    Fully coupled functional equations for the quark sector of QCD

    Fei Gao🇩🇪 · Joannis Papavassiliou🇪🇸 · Jan M. Pawlowski🇩🇪

    We present a comprehensive study of the quark sector of flavour QCD, based on a self-consistent treatment of the coupled system of Schwinger-Dyson equations for the quark propagator and the full quark-gluon vertex. The individual form factors of the quark-gluon vertex are expressed in a special tensor basis obtained from a set of gauge-invariant operators. The sole external ingredient used as input to our equations is the Landau gauge gluon propagator with dynamical quark flavours, obtained from studies with Schwinger-Dyson equations, the functional renormalisation group approach, and large volume lattice simulations. The appropriate renormalisation procedure required in order to self-consistently accommodate external inputs stemming from other functional approaches or the lattice is discussed in detail, and the value of the gauge coupling is accurately determined at two vastly separated renormalisation group scales. Our analysis establishes a clear hierarchy among the vertex form factors. We identify only three dominant ones, in agreement with previous results. The components of the quark propagator obtained from our approach are in excellent agreement with the results from Schwinger-Dyson equations, the functional renormalisation group, and lattice QCD simulation, a simple benchmark observable being the chiral condensate in the chiral limit, which is computed as . The present approach has a wide range of applications, including the self-consistent computation of bound-state properties and finite temperature and density physics, which are briefly discussed.

    Comments:
    72 pages, 30 figures. Version including minor changes of version published in PRD. For the benefit of the reader we have also added an Appendix, that contains many more details of the renormalization scheme (MOM scheme) used in this work. In particular we provide a comparison with MOM scheme results in the literature (Appendix A2), as well as the derivation of the RG scheme (Appendix A3)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    2102.13053 [pdf]
    PRD(2021)·105 citations
  2. 07

    [Submitted on 25 Feb 2021] (cross-list from hep-ph)

    Angular Distributions, Polarization Observables, Spin Density Matrices and Statistical Tensors in Photoproduction of Two Pseudoscalar Mesons off a Nucleon

    Hiram G. Menendez Santiago🇺🇸

    In two meson photoproduction off a nucleon, for the case in which two of the three final state hadrons are products of the decay of an intermediate resonance, general expressions for its decay distribution and for polarization observables are derived in a model independent way. These are functions of either the spin density matrix elements (SDME's) or statistical tensors of the resonance, and the angles of its decay products. The expressions are general enough that it also describes cases where more than one resonance of arbitrary quantum numbers contributes, including interference effects. They can therefore be used to extract the SDME's or statistical tensors of the resonances that contribute to the reaction.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2102.13104 [pdf]
    0 citations
  3. 08

    [Submitted on 25 Feb 2021] (cross-list from hep-ph)

    Test of the nonrelativistic potential

    Ulugbek Yakhshiev🇰🇷

    We analyze the charmonium states by testing a phenomenological nonrelativistic potential and propose a new set of parameters. This new set of parameters are fixed using only the lowest lying S-wave states of charmonia where the spin-orbit and tensor interactions will not contribute. After fitting the parameters we analyze the whole fine structure of charmonium states taking into account the spin-orbit and tensor interactions too. Calculations showed that the nonrelativistic potential model with the phenomenologically defined parameters is indeed well approximation for describing the charmonium states.

    Comments:
    5 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2102.13175 [pdf]
    J.Korean Phys.Soc.(2021)·3 citations
  4. 09

    [Submitted on 26 Feb 2021] (cross-list from astro-ph.HE)

    Bayesian analysis of multimessenger M-R data with interpolated hybrid EoS

    A. Ayriyan🇷🇺 · D. Blaschke🇵🇱 · A. G. Grunfeld🇦🇷 · D. Alvarez-Castillo🇷🇺 · H. Grigorian🇷🇺 · V. Abgaryan🇷🇺

    We introduce a family of equations of state (EoS) for hybrid neutron star (NS) matter that is obtained by a two-zone parabolic interpolation between a soft hadronic EoS at low densities and a set of stiff quark matter EoS at high densities within a finite region of chemical potentials . Fixing the hadronic EoS as the APR one and choosing the color-superconducting, nonlocal NJL model with two free parameters for the quark phase, we perform Bayesian analyses with this two-parameter family of hybrid EoS. Using three different sets of observational constraints that include the mass of PSR J0740+6620, the tidal deformability for GW170817, and the mass-radius relation for PSR J0030+0451 from NICER as obligatory (set 1), while set 2 uses the possible upper limit on the maximum mass from GW170817 as an additional constraint and set 3 instead of the possibility that the lighter object in the asymmetric binary merger GW190814 is a neutron star. We confirm that in any case, the quark matter phase has to be color superconducting with the dimensionless diquark coupling approximately fulfilling the Fierz relation and the most probable solutions exhibiting a proportionality between and , the coupling of the repulsive vector interaction that is required for a sufficiently large maximum mass. We used the Bayesian analysis to investigate with the method of fictitious measurements the consequences of anticipating different radii for the massive PSR J0740+6220 for the most likely equation of state. With the actual outcome of the NICER radius measurement on PSR J0740+6220 we could conclude that for the most likely hybrid star EoS would not support a maximum mass as large as so that the event GW190814 was a binary black hole merger.

    Comments:
    20 figures, 1 table, 18 pages
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2102.13485 [pdf]
    EPJA(2021)·64 citations

Affiliations

first authorsco-authorsvia INSPIRE