119299952
Third-order relativistic dissipative hydrodynamics
Following the procedure introduced by Israel and Stewart, we expand the entropy current up to the third order in the shear stress tensor $\pi^{\alpha\beta}$ and derive a novel third-order evolution equation for $\pi^{\alpha\beta}$. This equation is solved for the one-dimensional Bjorken boost-invariant expansion. The scaling solutions for various values of the shear viscosity to the entropy density ratio $\eta/s$ are shown to be in very good agreement with those obtained from kinetic transport calculations. For the pressure isotropy starting with 1 at $\tau_0=0.4 fm/c$, the third-order corrections to Israel-Stewart theory are approximately 10\% for $\eta/s=0.2$ and more than a factor of 2 for $\eta/s=3$. We also estimate all higher-order corrections to Israel-Stewart theory and demonstrate their importance in describing highly viscous matters.
119188254
Solving the heat-flow problem with transient relativistic fluid dynamics
Israel-Stewart theory is a causal, stable formulation of relativistic dissipative fluid dynamics. This theory has been shown to give a decent description of the dynamical behavior of a relativistic fluid in cases where shear stress becomes important. In principle, it should also be applicable to situations where heat flow becomes important. However, it has been shown that there are cases where Israel-Stewart theory cannot reproduce phenomena associated with heat flow. In this paper, we derive a relativistic dissipative fluid-dynamical theory from kinetic theory which provides a good description of all dissipative phenomena, including heat flow. We explicitly demonstrate this by comparing this theory with numerical solutions of the relativistic Boltzmann equation.
118651470
Elliptic flow and energy loss of heavy quarks in ultrarelativistic heavy ion collisions
the modifications we employed to the standard leading order cross section. In Sec. IV we show our results for RHIC and LHC and compare them to the experimental data where possible. Finally, we conclude with a short summary.
23996522
Extraction of shear viscosity in stationary states of relativistic particle systems.
Starting from a classical picture of shear viscosity we construct a stationary velocity gradient in a microscopic parton cascade. Employing the Navier-Stokes ansatz we extract the shear viscosity coefficient η. For elastic isotropic scatterings we find an excellent agreement with the analytic values. This confirms the applicability of this method. Furthermore, for both elastic and inelastic scatterings with pQCD based cross sections we extract the shear viscosity coefficient η for a pure gluonic system and find a good agreement with already published calculations.
119224614
Bulk matter evolution and extraction of jet transport parameter in heavy-ion collisions at RHIC
Xiao-Fang Chen, 2 Carsten Greiner, Enke Wang, Xin-Nian Wang, 2 and Zhe Xu 2 Institute of Particle Physics and Key Laboratory of Quark & Lepton Physics, Huazhong Normal University, Wuhan 430079, China Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main, Germany Nuclear Science Division, MS 70R0319, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, D-60438 Frankfurt am Main, Germany (Dated: February 5, 2010)
119114969
Thermalization of a color glass condensate and review of the 'Bottom-Up' scenario
Abstract The thermalization of a longitudinally expanding color glass condensate with Bjorken boost invariant geometry is investigated within microscopical parton cascade BAMPS. Our main focus lies on the detailed comparison of thermalization, observed in BAMPS with that suggested in the “bottom–up” scenario. We demonstrate that the tremendous production of soft gluons via g g → g g g , which is shown in the “bottom–up” picture as the dominant process during the early pre-equilibration, will not occur in heavy ion collisions at RHIC and LHC energies, because the back reaction g g g → g g hinders the absolute particle multiplication. Moreover, contrary to the “bottom–up” scenario, soft and hard gluons thermalize at the same time. The time scale of thermal equilibration in BAMPS calculations is of order α s −2 ( ln α s ) −2 Q s −1 . After this time the gluon system exhibits nearly hydrodynamical behavior. The shear viscosity to entropy density ratio has a weak dependence on Q s and lies close to the lower bound of the AdS/CFT conjecture.
55419754
A Beam Gas Vertex Detector for Beam Size Measurement in the LHC
The Beam Gas Vertex (BGV) detector is foreseen as a possible non-invasive beam size measurement instrument for the LHC and its luminosity upgrade. This technique is based on the reconstruction of beam-gas interaction vertices, where the charged particles produced in inelastic beam-gas interactions are measured with high-precision tracking detectors. The design studies and expected performance of the currently developed BGV prototype will be presented with an overview given of the associated vacuum, detector and readout systems. A brief description will be given of the BGV Monte Carlo simulation application, which is based on the LHCb computing framework (Gaudi) and allows simulation studies to be performed and online event reconstruction algorithms to be developed.