PaperPanorama
FAQ

Nuclear Theory·nucl-th

Monday·February 23, 2015

8 papers—4 primary·4 cross-listed

All8Primary4Cross-lists4
  1. 05

    [Submitted on 19 Feb 2015] (cross-list from hep-ph)

    QCD and Hadron Physics

    Stanley J. Brodsky🇺🇸 · Abhay L. Deshpande🇺🇸 · Haiyan Gao🇺🇸 · Robert D. McKeown🇺🇸 · Curtis A. Meyer🇺🇸 · Zein-Eddine Meziani🇺🇸 · Richard G. Milner🇺🇸 · Jianwei Qiu🇺🇸 · David G. Richards🇺🇸 · Craig D. Roberts🇺🇸

    This document presents the recommendations and scientific conclusions from the Town Meeting on QCD and Hadronic Physics that took place in the period 13-15 September 2014 at Temple University as part of the NSAC 2014 Long Range Planning process. It highlights progress in hadron physics in the seven years since the 2007 Long Range Plan (LRP07), and presents a vision for the future by identifying key questions and plausible paths to solutions which should define our next decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (roughly 5 years) and longer term (beyond 10 years) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential in hadronic physics worldwide. In this connection, the potential of an electron ion collider is highlighted.

    Comments:
    48 pages, 19 figures. Summary of the DNP Town Meeting, Temple University, 13-15 September 2014
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1502.05728 [pdf]
    36 citations
  2. 06

    [Submitted on 20 Feb 2015] (cross-list from hep-ph)

    Perfect fluidity of a dissipative system: Analytical solution for the Boltzmann equation in

    Jorge Noronha🇺🇸 · Gabriel S. Denicol🇨🇦

    In this paper we obtain an analytical solution of the relativistic Boltzmann equation under the relaxation time approximation that describes the out-of-equilibrium dynamics of a radially expanding massless gas. This solution is found by mapping this expanding system in flat spacetime to a static flow in the curved spacetime . We further derive explicit analytic expressions for the momentum dependence of the single particle distribution function as well as for the spatial dependence of its moments. We find that this dissipative system has the ability to flow as a perfect fluid even though its entropy density does not match the equilibrium form. The non-equilibrium contribution to the entropy density is shown to be due to higher order scalar moments (which possess no hydrodynamical interpretation) of the Boltzmann equation that can remain out of equilibrium but do not couple to the energy-momentum tensor of the system. Thus, in this system the slowly moving hydrodynamic degrees of freedom can exhibit true perfect fluidity while being totally decoupled from the fast moving, non-hydrodynamical microscopic degrees of freedom that lead to entropy production.

    Comments:
    17 pages, 2 figures; added reference, version accepted for publication in Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
    arXiv:
    1502.05892 [pdf]
    PRD(2015)·20 citations
  3. 07

    [Submitted on 20 Feb 2015] (cross-list from hep-th)

    Analytic solutions of the relativistic Boltzmann equation

    Yoshitaka Hatta🇯🇵 · Mauricio Martinez🇺🇸 · Bo-Wen Xiao🇨🇳

    We present new analytic solutions to the relativistic Boltzmann equation within the relaxation time approximation. We first obtain spherically expanding solutions which are the kinetic counterparts of the exact solutions of the Israel-Stewart equation in the literature. This allows us to compare the solutions of the kinetic and hydrodynamic equations at an analytical level. We then derive a novel boost-invariant solution of the Boltzmann equation which has an unconventional dependence on the proper time. The existence of such a solution is also suggested in second order hydrodynamics and fluid-gravity correspondence.

    Comments:
    18 pages.v3: update to match the published version
    Subjects:
    High Energy Physics — Theory (hep-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th); Fluid Dynamics (physics.flu-dyn)
    arXiv:
    1502.05894 [pdf]
    PRD(2015)·19 citations
  4. 08

    [Submitted on 20 Feb 2015] (cross-list from cond-mat.stat-mech)

    Linear Boltzmann-like equation, describing non-classical particle transport, and related asymptotic solutions for small mean free paths

    Sergey A. Rukolaine

    In classical kinetic or kinetic-like models a particle free path distribution is exponensial, but this is more likely to be an exception than a rule. In this paper we derive a linear Boltzmann-like equation for a general free path distribution in the framework of Alt's model J. Math. Biol. 9:147 (1980). In the special case that the free path distribution has at least first and second finite moments we construct an asymptotic solution of the equation for small mean free paths. The asymptotic solution becomes a diffusion approximation to the one-speed Boltzmann-like equation.

    Comments:
    14 pages
    Subjects:
    Statistical Mechanics (cond-mat.stat-mech); Mathematical Physics (math-ph); math.MP (math.MP); Nuclear Theory (nucl-th); physics.bio-ph (physics.bio-ph); q-bio.QM (q-bio.QM)
    arXiv:
    1502.05972 [pdf]
    Physica A(2016)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE