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Nuclear Theory·nucl-th

Friday·July 20, 2018

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 05

    [Submitted on 18 Jul 2018] (cross-list from hep-lat)

    Proton Isovector Helicity Distribution on the Lattice at Physical Pion Mass

    Huey-Wen Lin🇺🇸 · Jiunn-Wei Chen🇹🇼 · Xiangdong Ji🇨🇳 · Luchang Jin🇺🇸 · Ruizi Li🇺🇸 · Yu-Sheng Liu🇨🇳 · Yi-Bo Yang🇺🇸 · Jian-Hui Zhang🇩🇪 · Yong Zhao🇺🇸

    We present a state-of-the-art calculation of the isovector quark helicity Bjorken- distribution in the proton using lattice-QCD ensembles at the physical pion mass. We compute quasi-distributions at proton momenta ~GeV on the lattice, and match them systematically to the physical parton distribution using large-momentum effective theory (LaMET). We reach an unprecedented precision through high statistics in simulations, large-momentum proton matrix elements, and control of excited-state contamination. The resulting distribution with combined statistical and systematic errors is in agreement with the latest phenomenological analysis of the spin-dependent experimental data; in particular, .

    Comments:
    6 pages, 4 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1807.07431 [pdf]
    PRL(2018)·137 citations
  2. 06

    [Submitted on 19 Jul 2018] (cross-list from hep-ph)

    Bottomonium suppression at RHIC and LHC

    Brandon Krouppa🇺🇸 · Alexander Rothkopf🇳🇴 · Michael Strickland🇺🇸

    The strong suppression of heavy quarkonia is a good indicator that one has generated a quark-gluon plasma (QGP) in an ultrarelativistic heavy ion collision. Recent advancements in first principles calculations of the heavy quark potential provide additional insight into this suppression and can be used to further pin down the in-medium properties of the QGP. Realistic 3+1d dissipative hydrodynamical models can be used to simulate the QGP and, with bottomonium as a probe, one can make inferences for the initial temperature of the QGP and other phenomenological parameters such as the shear viscosity to entropy density ratio. However, progressing to LHC TeV Pb-Pb collisions, one expects regeneration to have an increasingly important impact on the suppression observables. In this proceedings, we present a brief overview to set up the model and then provide model results for bottomonium suppression and regeneration, for ultrarelativistic heavy-ion collision experiments at RHIC and LHC.

    Comments:
    4 pages, 6 figures; proceedings contribution to Quark Matter 2018, May 13-19 2018
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1807.07452 [pdf]
    NPA(2019)·11 citations
  3. 07

    [Submitted on 19 Jul 2018] (cross-list from nucl-ex)

    Distributions of the largest fragment size in multifragmentation: Traces of a phase transition

    J. Brzychczyk🇵🇱 · T. Pietrzak🇵🇱 · A. Wieloch🇵🇱 · W. Trautmann🇩🇪

    Distributions of the largest fragment charge are studied using the ALADIN data on fragmentation of Au projectiles at relativistic energies. The statistical measures skewness and kurtosis of higher-order fluctuations provide a robust indication of the transition point, linked to a phase transition in the thermodynamic limit. Extensive comparisons with predictions of a bond percolation model corroborate the high accuracy of this model in reproducing the distributions as well as the whole fragmentation pattern as represented by the measured charge correlations. In analogy to percolation, the pseudocritical and critical points are identified in the fragmentation data. Questions concerning the distinction between different models and between first- and second-order phase transitions are discussed.

    Comments:
    29 pages, 13 figures, submitted to Phys. Rev. C
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1807.07481 [pdf]
    PRC(2018)·6 citations
  4. 08

    [Submitted on 19 Jul 2018] (cross-list from hep-ph)

    Quasi-parton distribution functions: two-dimensional scalar and spinor QCD

    Xiangdong Ji🇺🇸 · Yizhuang Liu🇺🇸 · Ismail Zahed🇺🇸

    We construct the quasi-parton distributions of mesons for two-dimensional QCD with either scalar or spinor quarks using the expansion. We show that in the infinite momentum limit, the parton distribution function is recovered in both leading and sub-leading order in .

    Comments:
    8 pages
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1807.07528 [pdf]
    PRD(2019)·33 citations

Affiliations

first authorsco-authorsvia INSPIRE