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Nuclear Theory·nucl-th

Thursday·May 2, 2019

4 papers—1 primary·3 cross-listed

All4Primary1Cross-lists3
  1. 01

    [Submitted on 30 Apr 2019]

    On symmetries of Hamiltonians describing systems with arbitrary spins

    Michael J. Cervia · Amol V. Patwardhan · A.B. Balantekin

    We consider systems where dynamical variables are the generators of the SU(2) group. A subset of these Hamiltonians is exactly solvable using the Bethe ansatz techniques. We show that Bethe ansatz equations are equivalent to polynomial relationships between the operator invariants, or equivalently, between eigenvalues of those invariants.

    Comments:
    8 Pages of LATEX; Dedicated to the memory of E. Henley
    Subjects:
    Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); Quantum Physics (quant-ph)
    arXiv:
    1905.00082 [pdf]
    IJMPE(2019)·11 citations
  2. 02

    [Submitted on 30 Apr 2019] (cross-list from hep-ph)

    Meson-meson scattering in two-dimensional QCD

    Guo-Ying Chen🇨🇳 · Yingsheng Huang🇨🇳 · Yu Jia🇨🇳 · Rui Yu🇨🇳

    We extend the formalism pioneered by Callan, Coote and Gross to investigate the meson-meson scattering within the framework of 't Hooft model, i.e., the two-dimensional QCD in the limit. We derive the analytic expressions for various two-body meson-meson scattering amplitudes, concentrating on those quark diagrams which may be identified as the meson-meson contact interaction vertex in the context of the mesonic effective lagrangian in expansion. We also carry out a detailed numerical study for the meson-meson scattering for various quark flavors, and observe the near-threshold enhancement in some channels. This may be viewed as the hint of the existence of the tetra-quark state below two-meson threshold.

    Comments:
    15 pages, 14 figures, 1 table
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1904.13391 [pdf]
    0 citations
  3. 03

    [Submitted on 30 Apr 2019] (cross-list from astro-ph.HE)

    Cooling timescale for protoneutron stars and properties of nuclear matter: Effective mass and symmetry energy at high densities

    Ken'ichiro Nakazato🇯🇵 · Hideyuki Suzuki🇯🇵

    The cooling process of a protoneutron star is investigated with focus on its sensitivity to properties of hot and dense matter. An equation of state, which includes the nucleon effective mass and nuclear symmetry energy at twice the saturation density as control parameters, is constructed for systematic studies. The numerical code utilized in this study follows a quasi-static evolution of a protoneutron star solving the general-relativistic stellar structure with neutrino diffusion. The cooling timescale evaluated from the neutrino light curve is found to be longer for the models with larger effective masses and smaller symmetry energies at high densities. The present results are compared with those for other equations of state and it is found that they are consistent in terms of their dependences on the effective mass and neutron star radius.

    Comments:
    11 pages, 9 figures, accepted for publication in ApJ
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1905.00014 [pdf]
    ApJ(2019)·49 citations
  4. 04

    [Submitted on 30 Apr 2019] (cross-list from hep-th)

    Point-Particle Catalysis

    P. Hayman🇨🇦 · C.P. Burgess🇨🇦

    We use the point-particle effective field theory (PPEFT) framework to describe particle-conversion mediated by a flavour-changing coupling to a point-particle. We do this for a toy model of two non-relativistic scalars coupled to the same point-particle, on which there is a flavour-violating coupling. It is found that the point-particle couplings all must be renormalized with respect to a radial cut-off near the origin, and it is an invariant of the flow of the flavour-changing coupling that is directly related to particle-changing cross-sections. At the same time, we find an interesting dependence of those cross-sections on the ratio k_out/k_in of the outgoing and incoming momenta, which can lead to a 1/k_in enhancement in certain regimes. We further connect this model to the case of a single-particle non-self-adjoint (absorptive) PPEFT, as well as to a PPEFT of a single particle coupled to a two-state nucleus. These results could be relevant for future calculations of any more complicated reactions, such as nucleus-induced electron-muon conversions, monopole catalysis of baryon number violation, as well as nuclear transfer reactions.

    Comments:
    28 pages, 4 figures
    Subjects:
    High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1905.00103 [pdf]
    Front.in Phys.(2019)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE