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Nuclear Theory·nucl-th

Monday·December 7, 2015

5 papers—2 primary·3 cross-listed

All5Primary2Cross-lists3
  1. 03

    [Submitted on 4 Dec 2015] (cross-list from hep-ph)

    Spin Polarized Photons from Axially Charged Plasma at Weak Coupling: Complete Leading Order

    Kiminad A. Mamo🇺🇸 · Ho-Ung Yee🇺🇸

    In the presence of (approximately conserved) axial charge in the QCD plasma at finite temperature, the emitted photons are spin-aligned, which is a unique P- and CP-odd signature of axial charge in the photon emission observables. We compute this "P-odd photon emission rate" in weak coupling regime at high temperature limit to complete leading order in the QCD coupling constant: the leading log as well as the constant under the log. As in the P-even total emission rate in the literature, the computation of P-odd emission rate at leading order consists of three parts: 1) Compton and Pair Annihilation processes with hard momentum exchange, 2) soft t- and u-channel contributions with Hard Thermal Loop re-summation, 3) Landau-Pomeranchuk-Migdal (LPM) re-summation of collinear Bremstrahlung and Pair Annihilation. We present analytical and numerical evaluations of these contributions to our P-odd photon emission rate observable.

    Comments:
    41 pages, 11 figures; v2: one minor typo fixed, references added, accepted for publication in PRD
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1512.01316 [pdf]
    PRD(2016)·13 citations
  2. 04

    [Submitted on 4 Dec 2015] (cross-list from hep-th)

    Entanglement in Four-Dimensional SU(3) Gauge Theory

    Etsuko Itou🇯🇵 · Keitaro Nagata🇯🇵 · Yoshiyuki Nakagawa🇯🇵 · Atsushi Nakamura🇯🇵 · V.I. Zakharov🇷🇺

    We investigate the quantum entanglement entropy for the four-dimensional Euclidean SU(3) gauge theory. We present the first non-perturbative calculation of the entropic -function () of SU(3) gauge theory in lattice Monte Carlo simulation using the replica method. For ~fm, where is the length of the subspace, the entropic -function is almost constant, indicating conformally invariant dynamics. The value of the constant agrees with that perturbatively obtained from free gluons, with 20 % discrepancy. When is close to the Hadronic scale, the entropic -function decreases smoothly, and it is consistent with zero within error bars at fm.

    Comments:
    5 pages, 2figures
    Subjects:
    High Energy Physics — Theory (hep-th); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
    arXiv:
    1512.01334 [pdf]
    PTEP(2016)·65 citations
  3. 05

    [Submitted on 4 Dec 2015] (cross-list from hep-ph)

    An analysis of the impact of LHC Run I proton-lead data on nuclear parton densities

    Néstor Armesto🇪🇸 · Hannu Paukkunen🇪🇸 · José Manuel Penín🇪🇸 · Carlos A. Salgado🇪🇸 · Pía Zurita🇪🇸

    We report on an analysis of the impact of available experimental data on hard processes in proton-lead collisions during Run I at the Large Hadron Collider on nuclear modifications of parton distribution functions. Our analysis is restricted to the EPS09 and DSSZ global fits. The measurements that we consider comprise production of massive gauge bosons, jets, charged hadrons and pions. This is the first time a study of nuclear PDFs includes this number of different observables. The goal of the paper is twofold: i) checking the description of the data by nPDFs, as well as the relevance of these nuclear effects, in a quantitative manner; ii) testing the constraining power of these data in eventual global fits, for which we use the Bayesian reweighting technique. We find an overall good, even too good, description of the data, indicating that more constraining power would require a better control over the systematic uncertainties and/or the proper proton-proton reference from LHC Run II. Some of the observables, however, show sizable tension with specific choices of proton and nuclear PDFs. We also comment on the corresponding improvements on the theoretical treatment.

    Comments:
    20 pages, 10 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1512.01528 [pdf]
    EPJC(2016)·48 citations

Affiliations

first authorsco-authorsvia INSPIRE