Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

High Energy Physics and Microelectronics 913.1.2.4 Thermal radiation from Au + Au collisions at √ s = 200GeV/A energyThe transverse momentum distribution of the direct photons measured by the PHENIX collaborationin Au + Au collisions at √ s = 200 GeV/A has been analyzed. It has been shown that thedata can be reproduced reasonably well assuming a deconfined state of thermalized quarks andgluons formed at an initial time τ i =0.2 fm/c with initial temperature T i =400 MeV. The effectsof the modifications of hadronic properties have been taken into account in evaluating the photonspectra. We argue that the initial temperature of the system formed after the collision is more thanthe transition temperature for deconfinement obtained from lattice QCD simulations.JK Nayak†, J Alam†, P Roy, AK Dutt-Mazumder, B SinhaHEP3.1.2.5 Collisional energy loss and suppression of high p T hadronsWe calculate nuclear suppression factor (R AA ) for light hadrons by taking only the elastic processesand argue that in the measured p T domain of RHIC, collisional rather than the radiative processesis the dominant mechanism for partonic energy loss.J Alam†, P Roy, AK Dutt-MazumderHEP3.1.2.6 Can collisional energy loss explain nuclear suppression factor for lighthadrons?We argue that in the measured p T domain of RHIC, collisional rather than the radiative energyloss is the dominant mechanism for jet quenching. Accordingly we calculate nuclear suppressionfactor for light hadrons by taking only the elastic energy loss in sharp contrast with the previouscalculations where only the radiative loss are considered.J Alam†, P Roy, AK Dutt-MazumderHEP3.1.2.7 Matter induced charge symmetry breaking and pion form factor in nuclearmediumMedium modification of pion form factor has been evaluated in asymmetric nuclear matter. Itis shown that both the shape and the pole position of the pion form factor in dense asymmetricnuclear matter is different from its vacuum counterpart with ρ-ω mixing. This is due to the densityand asymmetry dependent ρ-ω mixing which could even dominate over its vacuum counterpartin matter. Effect of the in-medium pion factor on experimental observables e.g., invariant massdistribution of lepton pairs has been demonstrated.P Roy, J Alam†, AK Dutt-Mazumder, S Sarkar†HEP