[Kumar* et al., 5(8): August, 2016] ISSN: 2277-9655 IC™ Value: 3.00 Impact Factor: 4.116 http: // www.ijesrt.com © International Journal of Engineering Sciences & Research Technology [930] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY EFFECT OF EVOLUTION OF DIRECT PHOTONS ON THE VISCOSITY OF QUARK GLUON PLASMA Rakesh Kumar, Sunil Kumar Pandey Department of Physics, Institute of Engineering and Technology, NIMS University, Jaipur, Rajasthan, India. DOI: 10.5281/zenodo.60834 ABSTRACT The quark-gluon plasma at the stage of thermodynamic equilibrium is reviewed. The quark hadron phase transition and the color superconducting phases of quark-gluon matter with the help of phase diagram are discussed. The lattice QCD results on the order of the phase transition of QGP. We discuss some aspects of atomic Fermi gas in the unitary limit in the first order transition. We consider the equation of state and the critical temperature for pair condensation. The strongly interacting phase transition (Quark-Hadron phase transition) also discussed. KEYWORDS: Quark Gluon Plasma, Hadrons Suppression, Transport parameter, chemical potential, Baryon density, Lattice QCD, Equation of state. INTRODUCTION The RHIC experiment data confirmed that the noble state of matter called quark gluon plasma can be observed in nucleus-nucleus collisions at very high temperature and energy density. The hadrons emitted with large transverse momentum during central collisions and are strongly suppressed [1]. This suppression of hadrons is characterized by jet quenching and these suppressions results in the production of gluon by multiple collisions [2]. The collective flow of a medium is described by relativistic hydrodynamics [3]. The whole phenomenon is governed by transport parameter ݍ which is defined as the squared average transverse momentum exchange between the gluon medium and the fast parton per unit path length [4]. We would like to consider the strongly coupled classical plasma to study its qualitative features and photons production during nucleus collisions. The perturbative expansion can be explained by the interaction between hard jets and strongly interacting matter [5]. The parton gets excited in QCD coupling which makes weak coupling of QCD. This weak coupling of QCD referred to the partonic quasi particle picture. But, strong coupling vanishes this parton quasi particle picture. There exist a general relation between jet parameter ݍ and the coefficient of viscosity ߟ which indicate the weakly coupled plasma and responsible for the generation of viscosity of gluon medium. The interaction between quarks and gluons at some temperature T radiate photons. The production of photons confirms the strongly interacting nature of quark gluon plasma at RHIC. When the transverse momentum ݌  is lower than the plasma temperature, photons decays from ߨ ଴ . At large transverse momenta, the spectra for thermal photons fall rapidly. When ݌  is lower than ͵ , direct photons dominates. But the identification of these direct photons at this momenta range are much very difficult from the hadronic decay of ߨ ଴ . But when transverse momenta are greater than 3 GeV, direct photons can be identify and can measure the spectra. These high energy direct photons also generate virtual photons which soon convert into  +  − pairs.