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Nuclear Theory·nucl-th

Thursday·October 27, 2016

11 papers—6 primary·5 cross-listed

All11Primary6Cross-lists5
  1. 01

    Departure from Equilibrium of the Quasi-Particle Distribution Functions in High Energy Nuclear Collisions

    P. Chakraborty🇮🇳 · J. I. Kapusta🇺🇸

    In simulations of high energy heavy ion collisions that employ viscous hydrodynamics, single particle distributions are distorted from their thermal equilibrium form due to gradients in the flow velocity. These are closely related to the formulas for the shear and bulk viscosities in the quasi-particle approximation. Distorted single particle distributions are now commonly used to calculate the emission of photons and dilepton pairs, and in the late stage to calculate the conversion of a continuous fluid to individual particles. We show how distortions of the single particle distribution functions due to both shear and bulk viscous effects can be done rigorously in the quasi-particle approximation and illustrate it with the linear model at finite temperature.

    nucl-thPRC(2017)·9 citations
  2. 02

    Effects of the Lorentz invariance violation in Coulomb interaction in nuclei and atoms

    V.V. Flambaum🇩🇪 · M.V. Romalis🇺🇸

    Anisotropy in the speed of light that has been constrained by Michelson-Morley-type experiments also generates anisotropy in the Coulomb interactions. This anisotropy can manifest itself as an energy anisotropy in nuclear and atomic experiments. Here the experimental limits on Lorentz violation in 21Ne are used to improve the limits on the Lorentz symmetry in the photon sector, namely the anisotropy of the speed of light and the Coulomb interactions, by 7 orders of magnitude in comparison with previous experiments: the speed of light is isotropic to a part in E-28.

    nucl-thhep-phphysics.atom-phPRL(2017)·28 citations
  3. 03

    A microscopic rotational cranking model and its connection to conventional cranking and other collective rotational models

    P. Gulshani

    A microscopic time-reversal invariant cranking model (MCRM) for nuclear collective rotation about a single axis and its coupling to intrinsic motion is derived. The MCRM is derived by transforming the stationary nuclear Schrodinger equation using a collective rotation-intrinsic product wavefunction, imposing no constraints on the wavefunction and the nucleon coordinates, and using no relative co-ordinates. The derivatives of the collective-rotation angle are defined in terms of a combination of rigid and irrotational collective flows of the nucleons. The collective wavefunction is chosen to be an eigenstate of the angular momentum, yielding a MCRM Schrodinger equation for the intrinsic wavefunction that contains a cranking Coriolis energy term that is linear in the angular momentum and shear operators, a collective centrifugal energy term, and a rotation-fluctuation energy term. In absence of the irrotational-flow component and fluctuation energy term, the MCRM equation reduces to that of the conventional cranking model (CCRM), but with a dynamic rigid-flow angular velocity and rigid-flow centrifugal-energy term. The expectation of the angular momentum operator, which is the sum of the collective rotation angular momentum and the expectation of the angular momentum in the intrinsic state, would reduce to that in the CCRM if the collective rotation angular momentum were small. However, it is shown that, even for the simple case of the anisotropic harmonic oscillator mean-field potential in , the collective rotation angular momentum is not small in the current version of the MCRM, and that this problem needs further study. It is also shown that the MCRM Schrodinger equation is reducible to the equations of the particle-plus-rotor, phenomenological and microscopic collective rotation-vibration, and two-fluid semi-classical collective models.

    nucl-th2 citations
  4. 04

    Dynamics of Anti-Proton -- Protons and Anti-Proton -- Nucleus Reactions

    A. Galoyan🇷🇺 · A. Ribon🇨🇭 · V. Uzhinsky🇷🇺

    A short review of simulation results of anti-proton-proton and anti-proton-nucleus interactions within the framework of Geant4 FTF (Fritiof) model is presented. The model uses the main assumptions of the Quark-Gluon-String Model or Dual Parton Model. The model assumes production and fragmentation of quark-anti-quark and diquark-anti-diquark strings in the mentioned interactions. Key ingredients of the model are cross sections of string creation processes and an usage of the LUND string fragmentation algorithm. They allow one to satisfactory describe a large set of experimental data, especially, a strange particle production, Lambda hyperons and K mesons.

    nucl-thhep-phNucl.Theor.(2016)·4 citations
  5. 05

    Charge conservation effects for high order fluctuations

    Viktor Begun🇵🇱

    The exact charge conservation significantly impacts multiplicity fluctuations. The result depends strongly on the part of the system charge carried by the particles of interest. Along with the expected suppression of fluctuations for large systems, charge conservation may lead to negative skewness or kurtosis for small systems.

    nucl-thhep-phnucl-exActa Phys.Polon.Supp.(2017)·1 citation
  6. 06

    Constraints on rapidity-dependent initial conditions from charged particle pseudorapidity densities and two-particle correlations

    Weiyao Ke🇺🇸 · J. Scott Moreland🇺🇸 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸

    We study the initial three-dimensional spatial configuration of the quark-gluon plasma produced in relativistic heavy-ion collisions using centrality and rapidity-dependent measurements of charged particle pseudorapidity densities and two-particle correlations. A cumulant-generating function is used to parametrize the rapidity dependence of local entropy deposition and extend arbitrary boost-invariant initial conditions to nonzero beam rapidities. The model is compared to p+Pb and Pb+Pb single-particle distributions and systematically optimized using Bayesian parameter estimation to extract high-probability initial condition parameters. The optimized initial conditions are then compared to a number of experimental observables including two-particle rapidity correlations, the rapidity dependence of anisotropic flow, and event-plane decorrelations.

    nucl-thnucl-exPRC(2017)·73 citations

Affiliations

first authorsco-authorsvia INSPIRE