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Nuclear Theory·nucl-th

Wednesday·July 29, 2015

4 papers—2 primary·2 cross-listed

All4Primary2Cross-lists2
  1. 01

    [Submitted on 27 Jul 2015]

    Matching pion-nucleon Roy-Steiner equations to chiral perturbation theory

    Martin Hoferichter🇩🇪 · Jacobo Ruiz de Elvira🇩🇪 · Bastian Kubis🇩🇪 · Ulf-G. Meißner🇩🇪

    We match the results for the subthreshold parameters of pion-nucleon scattering obtained from a solution of Roy-Steiner equations to chiral perturbation theory up to next-to-next-to-next-to-leading order, to extract the pertinent low-energy constants including a comprehensive analysis of systematic uncertainties and correlations. We study the convergence of the chiral series by investigating the chiral expansion of threshold parameters up to the same order and discuss the role of the \Delta(1232) resonance in this context. Results for the low-energy constants are also presented in the counting scheme usually applied in chiral nuclear effective field theory, where they serve as crucial input to determine the long-range part of the nucleon-nucleon potential as well as three-nucleon forces.

    Comments:
    6 pages, 4 tables; version to appear in PRL
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
    arXiv:
    1507.07552 [pdf]
    PRL(2015)·216 citations
  2. 02

    [Submitted on 28 Jul 2015]

    Degenerate limit thermodynamics beyond leading order for models of dense matter

    Constantinos Constantinou🇩🇪 · Brian Muccioli🇺🇸 · Madappa Prakash🇺🇸 · James M. Lattimer🇺🇸

    Analytical formulas for next-to-leading order temperature corrections to the thermal state variables of interacting nucleons in bulk matter are derived in the degenerate limit. The formalism developed is applicable to a wide class of non-relativistic and relativistic models of hot and dense matter currently used in nuclear physics and astrophysics (supernovae, proto-neutron stars and neutron star mergers) as well as in condensed matter physics. We consider the general case of arbitrary dimensionality of momentum space and an arbitrary degree of relativity (for relativistic mean-field theoretical models). For non-relativistic zero-range interactions, knowledge of the Landau effective mass suffices to compute next-to-leading order effects, but in the case of finite-range interactions, momentum derivatives of the Landau effective mass function up to second order are required. Numerical computations are performed to compare results from our analytical formulas with the exact results for zero- and finite-range potential and relativistic mean-field theoretical models. In all cases, inclusion of next-to-leading order temperature effects substantially extends the ranges of partial degeneracy for which the analytical treatment remains valid.

    Comments:
    28 pages, 8 figures
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1507.07874 [pdf]
    Annals Phys.(2015)·23 citations
  3. 03

    [Submitted on 28 Jul 2015] (cross-list from hep-lat)

    Reply to "Comment on `Lattice determination of Sigma - Lambda mixing' "

    R. Horsley🇬🇧 · J. Najjar🇩🇪 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · D. Pleiter🇩🇪 · P.E.L. Rakow🇬🇧 · G. Schierholz🇩🇪 · A. Schiller🇩🇪 · H. Stüben🇩🇪 · J.M. Zanotti🇦🇺

    In this Reply, we respond to the above Comment. Our computation [Phys. Rev. D 91 (2015) 074512] only took into account pure QCD effects, arising from quark mass differences, so it is not surprising that there are discrepancies in isospin splittings and in the Sigma - Lambda mixing angle. We expect that these discrepancies will be smaller in a full calculation incorporating QED effects.

    Comments:
    5 pages
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1507.07825 [pdf]
    PRD(2015)·11 citations
  4. 04

    [Submitted on 28 Jul 2015] (cross-list from hep-ph)

    Analytic solution of the Boltzmann equation in an expanding system

    D. Bazow (Ohio State U.)🇺🇸 · G. S. Denicol (Brookhaven & McGill U.)🇨🇦 · U. Heinz (Ohio State U.)🇺🇸 · M. Martinez (Ohio State U.)🇺🇸 · J. Noronha (Sao Paulo U. & Columbia U.)🇧🇷

    For a massless gas with constant cross section in a homogeneous, isotropically expanding spacetime we reformulate the relativistic Boltzmann equation as a set of non-linear coupled moment equations. For a particular initial condition this set can be solved exactly, yielding the first analytical solution of the Boltzmann equation for an expanding system. The non-equilibrium behavior of this relativistic gas can be mapped onto that of a homogeneous, static non-relativistic gas of Maxwell molecules.

    Comments:
    5 pages, 1 figure; minor changes, accepted for publication in Phys. Rev. Lett
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
    arXiv:
    1507.07834 [pdf]
    PRL(2016)·73 citations

Affiliations

first authorsco-authorsvia INSPIRE