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Nuclear Theory·nucl-th

Monday·August 29, 2016

10 papers—6 primary·4 cross-listed

All10Primary6Cross-lists4
  1. 07

    [Submitted on 25 Aug 2016] (cross-list from hep-ph)

    Probing the hardest branching of jets in heavy ion collisions

    Yang-Ting Chien🇺🇸 · Ivan Vitev🇺🇸

    We present the first calculation of the momentum sharing and angular separation distributions between the leading subjets inside a reconstructed jet in heavy ion collisions. These observables are directly sensitive to the hardest branching in the process of jet formation and are, therefore, ideal for studying the early stage of the in-medium parton shower evolution. The modification of the momentum sharing and angular separation distributions in lead-lead relative to proton-proton collisions is evaluated using the leading-order medium-induced splitting functions obtained in the framework of soft-collinear effective theory with Glauber gluon interactions. Qualitative and in most cases quantitative agreement between theory and preliminary CMS measurements suggests that the parton shower in heavy ion collisions can be dramatically modified early in the branching history. We propose a new measurement which will illuminate the angular distribution of the hardest branching within jets in heavy ion collisions.

    Comments:
    5 pages, 6 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1608.07283 [pdf]
    PRL(2017)·129 citations
  2. 08

    [Submitted on 25 Aug 2016] (cross-list from hep-ph)

    Medium Induced Transverse Momentum Broadening in Hard Processes

    A. H. Mueller🇺🇸 · Bin Wu🇺🇸 · Bo-Wen Xiao🇨🇳 · Feng Yuan🇺🇸

    Using deep inelastic scattering on a large nucleus as an example, we consider the transverse momentum broadening of partons in hard processes in the presence of medium. We find that one can factorize the vacuum radiation contribution and medium related broadening effects into the Sudakov factor and medium dependent distributions, respectively. Our derivations can be generalized to other hard processes, such as dijet productions, which can be used as a probe to measure the medium broadening effects in heavy ion collisions when Sudakov effects are not overwhelming.

    Comments:
    16 pages, 8 figures; v2, minor revision
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1608.07339 [pdf]
    PRD(2017)·54 citations
  3. 09

    [Submitted on 26 Aug 2016] (cross-list from hep-ph)

    Directed flow in heavy-ion collisions at NICA: what is interesting to measure?

    L.V. Bravina🇳🇴 · E.E. Zabrodin🇳🇴

    We study the formation of the directed flow of hadrons in nuclear collisions at energies between AGS and SPS in Monte Carlo cascade model. The slope of the proton flow at midrapidity tends to zero (softening) with increasing impact parameter of the collision. For very peripheral topologies this slope becomes negative (antiflow). The effect is caused by rescattering of hadrons in remnants of the colliding nuclei. Since the softening of the proton flow can be misinterpreted as indication of the presence of quark-gluon plasma, we propose several measurements at NICA facility which can help one to distinguish between the cases with and without the plasma formation.

    Comments:
    5 pages, 3 figures, Contribution to the NICA White Paper (EPJA, topical issue)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1608.07416 [pdf]
    EPJA(2016)·7 citations
  4. 10

    [Submitted on 26 Aug 2016] (cross-list from astro-ph.HE)

    A lower limit on the heat capacity of the neutron star core

    Andrew Cumming · Edward F. Brown · Farrukh J. Fattoyev · C. J. Horowitz · Dany Page · Sanjay Reddy

    We show that observations of the core temperature of transiently-accreting neutron stars combined with observations of an accretion outburst give a lower limit to the neutron star core heat capacity. For the neutron stars in the low mass X-ray binaries KS 1731-260, MXB 1659-29, and XTE J1701-462, we show that the lower limit is a factor of a few below the core heat capacity expected if neutrons and protons in the core are paired, so that electrons provide the dominant contribution to the heat capacity. This limit rules out a core dominated by a quark color-flavor-locked (CFL) phase, which would have a much lower heat capacity. Future observations of or limits on cooling during quiescence will further constrain the core heat capacity.

    Comments:
    14 pages, 10 figures, submitted to Physical Review C
    Subjects:
    High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
    arXiv:
    1608.07532 [pdf]
    PRC(2017)·71 citations

Affiliations

first authorsco-authorsvia INSPIRE