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Nuclear Theory·nucl-th

Friday·August 14, 2020

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 05

    [Submitted on 13 Aug 2020] (cross-list from hep-ph)

    Sum rule for the Compton amplitude and implications for the proton-neutron mass difference

    J. Gasser (U. Bern, AEC)🇨🇭 · H. Leutwyler (U. Bern, AEC)🇨🇭 · A. Rusetsky (U. Bonn, BCTP)🇩🇪

    The Cottingham formula expresses the leading contribution of the electromagnetic interaction to the proton-neutron mass difference as an integral over the forward Compton amplitude. Since quarks and gluons reggeize, the dispersive representation of this amplitude requires a subtraction. We assume that the asymptotic behaviour is dominated by Reggeon exchange. This leads to a sum rule that expresses the subtraction function in terms of measurable quantities. The evaluation of this sum rule leads to .

    Comments:
    26 pages, 9 figures. Update, matches the version published in EPJC
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    2008.05806 [pdf]
    EPJC(2020)·28 citations
  2. 06

    [Submitted on 13 Aug 2020] (cross-list from hep-ph)

    Particle Production in AgAg Collisions at GeV within a Hadronic Transport Approach

    Jan Staudenmaier🇩🇪 · Natey Kübler🇩🇪 · Hannah Elfner🇩🇪

    Heavy-ion collisions at low beam energies explore the high density regime of strongly-interacting matter. The dynamical evolution of these collisions can be successfully described by hadronic transport approaches. In March 2019, the HADES collaboration has taken data for AgAg collisions at GeV and in this work, we provide predictions for particle production and spectra within the Simulating Many Accelerated Strongly-interacting Hadrons (SMASH) approach. The multiplicities and spectra of strange and non-strange particles follow the expected trends as a function of system size. In particular, in AuAu collisions, much higher yields of double-strange baryons were observed experimentally than expected from a thermal model. Therefore, we incorporate a previously suggested mechanism to produce baryons via rare decays of high mass resonances and predict the multiplicities. In addition, we predict the invariant mass spectrum for dilepton emission and explore the most important sources of dileptons above 1 GeV, that are expected to indicate the temperature of the medium. Interestingly, the overall dilepton emission is very similar to the one in AuAu collisions at GeV, a hint that the smaller system at a higher energy behaves very similar to the larger system at lower beam energy.

    Comments:
    13 pages, 13 figures, text files with the data to reproduce the figures provided in source; replaced with published version, only minor changes and 1 figure removed
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    2008.05813 [pdf]
    PRC(2021)·12 citations
  3. 07

    [Submitted on 13 Aug 2020] (cross-list from hep-ph)

    Renormalization Group Studies of Dense Relativistic Systems

    Jens Braun🇩🇪 · Timon Dörnfeld🇩🇪 · Benedikt Schallmo🇩🇪 · Sebastian Töpfel🇩🇪

    Dense relativistic matter has attracted a lot of attention over many decades now, with a focus on an understanding of the phase structure and thermodynamics of dense strong-interaction matter. The analysis of dense strong-interaction matter is complicated by the fact that the system is expected to undergo a transition from a regime governed by spontaneous chiral symmetry breaking at low densities to a regime governed by the presence of a Cooper instability at intermediate and high densities. Renormalization group (RG) approaches have played and still play a prominent role in studies of dense matter in general. In the present work, we study RG flows of dense relativistic systems in the presence of a Cooper instability and analyze the role of the Silver-Blaze property. In particular, we critically assess how to apply the derivative expansion to study dense-matter systems in a systematic fashion. This also involves a detailed discussion of regularization schemes. Guided by these formal developments, we introduce a new class of regulator functions for functional RG studies which is suitable to deal with the presence of a Cooper instability in relativistic theories. We close by demonstrating its application with the aid of a simple quark-diquark model.

    Comments:
    19 pages, 3 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2008.05978 [pdf]
    PRD(2021)·37 citations

Affiliations

first authorsco-authorsvia INSPIRE