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Nuclear Theory·nucl-th

Monday·February 6, 2017

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 01

    [Submitted on 3 Feb 2017]

    Probing the exotic structure of B by its elastic scattering and breakup reaction on nuclear targets

    V.K. Lukyanov · D.N. Kadrev · E.V. Zemlyanaya · K.V. Lukyanov · A.N. Antonov · M.K. Gaidarov · K. Spasova

    The structure of the exotic B nucleus is studied by means of elastic scattering, as well as its breakup on nuclear targets. We present microscopic calculations of the optical potentials (OPs) and cross sections of elastic scattering of B on C, Ni, and Pb targets at energies MeV. The density distributions of B obtained within the variational Monte Carlo (VMC) model and the three-cluster model (3CM) are used to construct the potentials. The real part of the hybrid OP is calculated using the folding model with the direct and exchange terms included, while the imaginary part is obtained on the base of the high-energy approximation (HEA) and also taken to be equal to the microscopic real part of the OP. In this model the only free parameters are the depths of the real and imaginary parts of OP obtained by fitting the elastic scattering experimental data. It is found a dependence of their values on the model density of B. In addition, cluster model, in which B consists of a -halo and the Be core, is applied to calculate the breakup cross sections of B nucleus on Be, C, and Au targets, as well as momentum distributions of Be fragments, and a comparison with the existing experimental data is made.

    Comments:
    12 pages, 11 figures, 5 tables, accepted for publication in European Physical Journal A
    Subjects:
    Nuclear Theory (nucl-th)
    arXiv:
    1702.00927 [pdf]
    EPJA(2017)·11 citations
  2. 02

    [Submitted on 3 Feb 2017]

    Four-body calculation of and reactions above breakup threshold

    A. Deltuva · A. C. Fonseca

    Nucleon transfer reactions in deuteron-deuteron collisions at energies above the three- and four-body breakup threshold are described using exact four-body equations for transition operators that are solved in the momentum-space framework. Differential cross sections, analyzing powers, polarizations, and spin transfer coefficients are obtained using realistic two-nucleon potentials and including the Coulomb repulsion between protons. Overall good agreement between predictions and experimental data is found. Most remarkable discrepancies are seen around the minima of the differential cross section at higher energies and in the outgoing nucleon polarization at lower energies.

    Comments:
    7 pages, 7 figures, to be published in Phys. Rev. C. arXiv admin note: text overlap with arXiv:1508.00336
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    1702.01034 [pdf]
    PRC(2017)·31 citations
  3. 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
  4. 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
  5. 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