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Nuclear Theory·nucl-th

Thursday·June 25, 2015

7 papers—4 primary·3 cross-listed

All7Primary4Cross-lists3
  1. 05

    [Submitted on 23 Jun 2015] (cross-list from hep-ph)

    Light-Like Wilson Line in QCD Without Path Ordering

    Gouranga C. Nayak🇺🇸

    Unlike the Wilson line in QED the Wilson line in QCD contains path ordering. In this paper we get rid of the path ordering in the light-like Wilson line in QCD by simplifying all the infinite number of non-commuting terms in the SU(3) pure gauge. We prove that the light-like Wilson line in QCD naturally emerges when path integral formulation of QCD is used to prove factorization of soft and collinear divergences at all order in coupling constant in QCD processes at high energy colliders.

    Comments:
    Final Version, 20 pages latex, Accepted for publication in Phys. Part. Nucl. Lett. arXiv admin note: substantial text overlap with arXiv:1506.02651, arXiv:1506.02593
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1506.07146 [pdf]
    Phys.Part.Nucl.Lett.(2016)·31 citations
  2. 06

    [Submitted on 24 Jun 2015] (cross-list from hep-ph)

    Scattering off the Color Glass Condensate

    Heikki Mäntysaari🇫🇮

    In this thesis the Color Glass Condensate (CGC) framework, which describes quantum chromodynamics (QCD) at high energy, is applied to various scattering processes. Higher order corrections to the CGC evolution equations, known as the BK and JIMWLK equations, are also considered. It is shown that the leading order CGC calculations describe the experimental data from electron-proton deep inelastic scattering (DIS), proton-proton and proton-nucleus collisions. The initial condition for the BK evolution equation is obtained by performing a fit to deep inelastic scattering data. The fit result is used as an input to calculations of single particle spectra and nuclear suppression in proton-proton and proton-nucleus collisions, which are shown to be in agreement with RHIC and LHC measurements. In particular, the importance of a proper description of the nuclear geometry consistently with the DIS data fits is emphasized, as it results in a nuclear suppression factor which is consistent with the available experimental data. In addition to single particle production, the correlations between two hadrons at forward rapidity are computed. The RHIC measurements are shown to be naturally explainable in the CGC framework, and the previous CGC calculations are improved by including the so called inelastic and double parton scattering contributions. This improvement is shown to be required in order to get results compatible with the experimentally measured correlations. Exclusive vector meson production, which can be a powerful tool to study the gluonic structure of nuclei at small Bjorken-, is also considered. The cross sections are calculated within the CGC framework in the context of a future electron-ion collider. In particular, the cross section for incoherent diffractive vector meson production is derived and a centrality estimator for this process is proposed.

    Comments:
    PhD thesis, 98 pages. ISBN 978-951-39-6175-6
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1506.07313 [pdf]
    4 citations
  3. 07

    [Submitted on 24 Jun 2015] (cross-list from hep-ph)

    Investigating the domain of validity of the Gubser solution to the Boltzmann equation

    Ulrich W. Heinz🇺🇸 · Mauricio Martinez🇺🇸

    We study the evolution of the one particle distribution function that solves exactly the relativistic Boltzmann equation within the relaxation time approximation for a conformal system undergoing simultaneously azimuthally symmetric transverse and boost-invariant longitudinal expansion. We show, for arbitrary values of the shear viscosity to entropy density ratio, that the distribution function can become negative in certain kinematic regions of the available phase space depending on the boundary conditions. For thermal equilibrium initial conditions, we determine numerically the physical boundary in phase space where the distribution function is always positive definite. The requirement of positivity of this particular exact solution restricts its domain of validity, and it imposes physical constraints on its applicability.

    Comments:
    17 pages, 6 figures. v2: Minor corrections in the text. Updated references. Published version
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Statistical Mechanics (cond-mat.stat-mech); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1506.07500 [pdf]
    NPA(2015)·11 citations

Affiliations

first authorsco-authorsvia INSPIRE