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Nuclear Theory·nucl-th

Monday·February 6, 2017

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 03

    [Submitted on 2 Feb 2017] (cross-list from astro-ph.HE)

    Bayesian analysis for a new class of hybrid EoS models using mass and radius data of compact stars

    A. Ayriyan🇷🇺 · D. E. Alvarez-Castillo🇷🇺 · S. Benic🇯🇵 · D. Blaschke🇷🇺 · H. Grigorian🇦🇲 · S. Typel🇩🇪

    We present a Bayesian analysis for a new class of realistic models of two-phase equations of state (EoS) for hybrid stars and demonstrate that the observation of a pair of high-mass twin stars would have a sufficient discriminating power to favor hybrid EoS with a strong first order phase transition over alternative EoS. Such a measurement would provide evidence for the existence of a critical endpoint in the QCD phase diagram.

    Comments:
    6 pages, 2 figures, 1 scheme, contribution to the Proceedings of the International Conference on Critical Point and Onset of Deconfinement (CPOD'2016), Wroclaw, Poland, May 29 - June 5, 2016
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1702.00801 [pdf]
    Acta Phys.Polon.Supp.B(2017)·4 citations
  2. 04

    [Submitted on 3 Feb 2017] (cross-list from hep-ph)

    On the upper bound of entropy production rate from particle multiplicity in heavy ion collisions

    Mateusz Ploskon (LBNL, Berkeley)🇺🇸 · Martin Veselsky (SAOS, Bratislava)🇸🇰

    We provide a simple derivation for particle production in heavy-ion collisions that is proportional to the rate of entropy production. We find that the particle production depends only on the power of the centre-of-mass collision energy and the effective phase-space/volume (e.g. geometry of the collision approximated by the number of nucleons participating in the collision ). We show that at low-energies the pseudo-rapidity density of particles per participating nucleon pair scales linearly with while at high-energies with . The region is directly related to sub-nucleon degrees of freedom and creation of a quark-gluon plasma (QGP). This picture explains experimental observation that the shape of the distributions of pseudorapidity-density per nucleon pair of charged particles does not depend on over a large span of collision energies. We provide an explanation of the scaling and connect it with the maximum rate per unit time of entropy production. We conclude with remarks on the hadron-parton phase transition. In particular, our considerations suggest that the pseudo-rapitidy density of the produced particles per larger than approximately 1 (excluding particles from jet fragmentation) is a signature of a QGP formation.

    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1702.01103 [pdf]
    2 citations
  3. 05

    [Submitted on 3 Feb 2017] (cross-list from hep-lat)

    Constraining the hadronic spectrum through QCD thermodynamics on the lattice

    Paolo Alba🇩🇪 · Rene Bellwied🇺🇸 · Szabolcs Borsanyi🇩🇪 · Zoltan Fodor🇩🇪 · Jana Guenther🇩🇪 · Sandor D. Katz🇭🇺 · Valentina Mantovani Sarti🇮🇹 · Jacquelyn Noronha-Hostler🇺🇸 · Paolo Parotto🇺🇸 · Attila Pasztor🇩🇪 · Israel Portillo Vazquez🇺🇸 · Claudia Ratti🇺🇸

    Fluctuations of conserved charges allow to study the chemical composition of hadronic matter. A comparison between lattice simulations and the Hadron Resonance Gas (HRG) model suggested the existence of missing strange resonances. To clarify this issue we calculate the partial pressures of mesons and baryons with different strangeness quantum numbers using lattice simulations in the confined phase of QCD. In order to make this calculation feasible, we perform simulations at imaginary strangeness chemical potentials. We systematically study the effect of different hadronic spectra on thermodynamic observables in the HRG model and compare to lattice QCD results. We show that, for each hadronic sector, the well established states are not enough in order to have agreement with the lattice results. Additional states, either listed in the Particle Data Group booklet (PDG) but not well established, or predicted by the Quark Model (QM), are necessary in order to reproduce the lattice data. For mesons, it appears that the PDG and the quark model do not list enough strange mesons, or that, in this sector, interactions beyond those included in the HRG model are needed to reproduce the lattice QCD results.

    Comments:
    9 pages, 9 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1702.01113 [pdf]
    PRD(2017)·154 citations

Affiliations

first authorsco-authorsvia INSPIRE