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Nuclear Theory·nucl-th

Friday·December 1, 2017

8 papers—5 primary·3 cross-listed

All8Primary5Cross-lists3
  1. 06

    [Submitted on 30 Nov 2017] (cross-list from hep-ph)

    Prompt photon yield and coefficient from gluon fusion induced by magnetic field in heavy-ion collision

    Jorge David Castaño-Yepes🇲🇽 · Alejandro Ayala🇿🇦 · C. A. Dominguez🇿🇦 · L. A. Hernández🇲🇽 · Saúl Hernández-Ortíz🇲🇽 · María Elena Tejeda-Yeomans🇲🇽

    We compute the production of prompt photons and the harmonic coefficient in relativistic heavy-ion collisions induced by gluon fusion in the presence of an intense magnetic field, during the early stages of the reaction. The calculations take into account several parameters which are relevant to the description of the experimental transverse momentum distribution, and elliptic flow for RHIC and LHC energies. The main imput is the strength of the magnetic field which varies in magnitude from 1 to 3 times the pion mass squared, and allows the gluon fusion that otherwise is forbidden in the absence of the field. The high gluon occupation number and the value of the saturation scale also play an important role in our calculation, as well as a flow velocity and geometrical factors. Our results support the idea that the origin of at least some of the photon excess observed in heavy-ion experiments may arise from magnetic field induced processes, and gives a good description of the experimental data.

    Comments:
    6 pages, 2 figures, conference paper from ISMD 2017
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1711.11163 [pdf]
    EPJ Web Conf.(2018)·0 citations
  2. 07

    [Submitted on 30 Nov 2017] (cross-list from hep-ph)

    Strange matter in compact stars

    Thomas Klaehn🇺🇸 · David Blaschke🇷🇺

    We discuss possible scenarios for the existence of strange matter in compact stars. The appearance of hyperons leads to a hyperon puzzle in ab-initio approaches based on effective baryon-baryon potentials but is not a severe problem in relativistic mean field models. In general, the puzzle can be resolved in a natural way if hadronic matter gets stiffened at supersaturation densities, an effect based on the quark Pauli quenching between hadrons. We explain the conflict between the necessity to implement dynamical chiral symmetry breaking into a model description and the conditions for the appearance of absolutely stable strange quark matter that require both, approximately masslessness of quarks and a mechanism of confinement. The role of strangeness in compact stars (hadronic or quark matter realizations) remains unsettled. It is not excluded that strangeness plays no role in compact stars at all. To answer the question whether the case of absolutely stable strange quark matter can be excluded on theoretical grounds requires an understanding of dense matter that we have not yet reached.

    Comments:
    8 pages, 1 figure, accepted for publication in Proceedings of "Strangeness in Quark Matter 2017", Utrecht (EPJ WoC)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1711.11260 [pdf]
    EPJ Web Conf.(2018)·8 citations
  3. 08

    [Submitted on 30 Nov 2017] (cross-list from hep-ph)

    A Nakanishi-based model illustrating the covariant extension of the pion GPD overlap representation and its ambiguities

    N. Chouika🇫🇷 · C. Mezrag🇮🇹 · H. Moutarde🇫🇷 · J. Rodríguez-Quintero🇪🇸

    A systematic approach for the model building of Generalized Parton Distributions (GPDs), based on their overlap representation within the DGLAP kinematic region and a further covariant extension to the ERBL one, is applied to the valence-quark pion's case, using light-front wave functions inspired by the Nakanishi representation of the pion's Bethe-Salpeter amplitudes (BSA). This simple but fruitful pion's GPD model illustrates the general model building technique and, in addition, allows for the ambiguities related to the covariant extension, grounded on the Double Distribution (DD) representation, to be constrained by requiring a soft-pion theorem to be properly observed.

    Comments:
    8 pages, 4 figures, matches published version + typo correction
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1711.11548 [pdf]
    PLB(2018)·58 citations

Affiliations

first authorsco-authorsvia INSPIRE