scholarly journals Backreaction effects due to matter coupled higher derivative gravity

2015 ◽  
Vol 30 (16) ◽  
pp. 1550065 ◽  
Author(s):  
Lata Kh Joshi ◽  
P. Ramadevi
Keyword(s):  
Shear Viscosity ◽  
Quark Gluon Plasma ◽  
Transport Coefficients ◽  
Gluon Plasma ◽  
Entropy Density ◽  
Flow Measurements ◽  
Strongly Coupled ◽  
Higher Derivative ◽  
Scalar Matter ◽  
Dimensional Spacetime

AdS-hydrodynamics has proven to be a useful tool for obtaining transport coefficients observed in the collective flow of strongly coupled fluids like quark gluon plasma (QGP). Particularly, the ratio of shear viscosity to entropy density η/s obtained from elliptic flow measurements can be matched with the computation done in the dual gravity theory. The experimentally observed temperature dependence of η/s requires the study of scalar matter coupled AdS gravity including higher derivative curvature corrections. We obtain the backreaction to the metric for such a matter coupled AdS gravity in D-dimensional spacetime due to the higher derivative curvature corrections. Then, we present the backreaction corrections to shear viscosity η and entropy density s.

scholarly journals Drag force on heavy quarks and spatial string tension

2018 ◽  
Vol 33 (06) ◽  
pp. 1850041 ◽  
Author(s):  
Oleg Andreev
Keyword(s):  
String Duality ◽  
Drag Coefficient ◽  
Heavy Quark ◽  
Quark Gluon Plasma ◽  
Diffusion Coefficients ◽  
Transport Coefficients ◽  
Gluon Plasma ◽  
String Tension ◽  
Heavy Quarks ◽  
Strongly Coupled

Heavy quark transport coefficients in a strongly coupled Quark–Gluon Plasma can be evaluated using a gauge/string duality and lattice QCD. Via this duality, one can argue that for low momenta the drag coefficient for heavy quarks is proportional to the spatial string tension. Such a tension is well-studied on the lattice that allows one to straightforwardly make non-perturbative estimates of the heavy quark diffusion coefficients near the critical point. The obtained results are consistent with those in the literature.

scholarly journals THE SHEAR VISCOSITY TO ENTROPY RATIO: A STATUS REPORT

2011 ◽  
Vol 25 (23) ◽  
pp. 1867-1888 ◽  
Author(s):  
SERA CREMONINI
Keyword(s):  
Lower Bound ◽  
Shear Viscosity ◽  
Entropy Density ◽  
Status Report ◽  
Strongly Coupled ◽  
Higher Derivative ◽  
Universal Ratio ◽  
Gauge Gravity ◽  
Gravity Duality ◽  
Insight Into

This review highlights some of the lessons that the holographic gauge/gravity duality has taught us regarding the behavior of the shear viscosity to entropy density in strongly coupled field theories. The viscosity to entropy ratio has been shown to take on a very simple universal value in all gauge theories with an Einstein gravity dual. Here we describe the origin of this universal ratio, and focus on how it is modified by generic higher derivative corrections corresponding to curvature corrections on the gravity side of the duality. In particular, certain curvature corrections are known to push the viscosity to entropy ratio below its universal value. This disproves a longstanding conjecture that such a universal value represents a strict lower bound for any fluid in nature. We discuss the main developments that have led to insight into the violation of this bound, and consider whether the consistency of the theory is responsible for setting a fundamental lower bound on the viscosity to entropy ratio.

scholarly journals Anisotropic Flow Measurements at RHIC

KnE Energy ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 178
Author(s):  
A Taranenko
Keyword(s):  
Strong Evidence ◽  
Quark Gluon Plasma ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Rhic Energy ◽  
Relativistic Heavy Ion Collisions ◽  
Flow Measurements ◽  
Strongly Coupled ◽  
Anisotropic Flow ◽  
Ion Collisions

Anisotropic flow measurements in relativistic-heavy ion collisions at RHIC-BNL and LHC-CERN have provided strong evidence for the formation of a strongly coupled Quark-Gluon Plasma (sQGP). In this article, we briefly review and discuss the recent results of anisotropic flow measurements from the STAR and PHENIX experiments at RHIC, such as 1) new measurements at top RHIC energy √

scholarly journals Exploring the Partonic Phase at Finite Chemical Potential in and out-of Equilibrium

Particles ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 178-192 ◽  
Author(s):  
O. Soloveva ◽  
P. Moreau ◽  
L. Oliva ◽  
V. Voronyuk ◽  
V. Kireyeu ◽  
...  
Keyword(s):  
Cross Sections ◽  
Chemical Potential ◽  
Transport Coefficients ◽  
Gluon Plasma ◽  
Entropy Density ◽  
Baryon Chemical Potential ◽  
Equilibrium Study ◽  
200 Gev ◽  
Quasiparticle Model ◽  
Scattering Cross Sections

We study the influence of the baryon chemical potential μ B on the properties of the Quark–Gluon–Plasma (QGP) in and out-of equilibrium. The description of the QGP in equilibrium is based on the effective propagators and couplings from the Dynamical QuasiParticle Model (DQPM) that is matched to reproduce the equation-of-state of the partonic system above the deconfinement temperature T c from lattice Quantum Chromodynamics (QCD). We study the transport coefficients such as the ratio of shear viscosity η and bulk viscosity ζ over entropy density s, i.e., η / s and ζ / s in the ( T , μ ) plane and compare to other model results available at μ B = 0 . The out-of equilibrium study of the QGP is performed within the Parton–Hadron–String Dynamics (PHSD) transport approach extended in the partonic sector by explicitly calculating the total and differential partonic scattering cross sections based on the DQPM and the evaluated at actual temperature T and baryon chemical potential μ B in each individual space-time cell where partonic scattering takes place. The traces of their μ B dependences are investigated in different observables for symmetric Au + Au and asymmetric Cu + Au collisions such as rapidity and m T -distributions and directed and elliptic flow coefficients v 1 , v 2 in the energy range 7.7 GeV ≤ s N N ≤ 200 GeV.

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