Jan-e Alam

Thermal Photons and Lepton Pairs from Quark Gluon Plasma and Hot Hadronic Matter

Abstract The formulation of the real and virtual photon production rate from strongly interacting matter is presented in the framework of finite temperature field theory. The changes in the hadronic spectral function induced by temperature are discussed within the ambit of the Walecka type model, gauged linear and non-linear sigma models, hidden local symmetry approach, and QCD sum rule approach. The possibility of observing the direct thermal photon and lepton pairs from quark gluon plasma has been contrasted with those from hot hadronic matter with and without medium effects for various mass variation scenarios. At SPS energies, in-medium effects of different magnitude on the hadronic properties for the Walecka model, Brown–Rho scaling, and Nambu scaling scenarios are conspicuously visible through the low invariant mass distribution of dileptons and transverse momentum spectra of photons. However, at RHIC energies the thermal photon (dilepton) spectra originating from quark gluon plasma overshines those from hadronic matter for large transverse momentum (invariant mass) irrespective of the models used for evaluating the finite temperature effects on the hadronic properties. It is thus expected that at both RHIC and LHC energies the formation of quark gluon plasma in the initial stages may indeed turn out to be a realistic scenario.

Electromagnetic probes of quark gluon plasma

Abstract In very energetic collisions of heavy ions, a novel state of matter — quark gluon plasma — is expected to be transiently formed. We review the suitability of electromagnetically interacting particles, dilepton pairs, single photons, diphotons, etc., as diagnostic tools for quark gluon plasma.

Stopping power of hot QCD plasma

The partonic energy loss has been calculated taking both the hard and soft contributions for all the

PHOTONS FROM HADRONIC MATTER AT FINITE TEMPERATURE

2\ensuremath{\rightarrow}2

Velocity of sound in relativistic heavy ion collisions

processes, revealing the importance of the individual channels. Cancellation of the intermediate separation scale has been exhibited. Subtleties related to the identical final state partons have properly been taken into account. The estimated collisional loss is compared with its radiative counter part. We show that there exists a critical energy (

Relics of the cosmological QCD phase transition

{E}_{c}

Heavy-quark transport coefficients in a hot viscous quark–gluon plasma medium

) below which the collisional loss is more than its radiative counterpart. In addition, we present closed form formulas for both the collision probabilities and the stopping power (

Indication of a coexisting phase of quarks and hadrons in nucleus-nucleus collisions

dE/dx

Electromagnetic radiation from hot and dense hadronic matter

).

Quark Nuggets as Baryonic Dark Matter

Abstract Temperature dependence of hadronic decay widths and masses are studied within the framework of an effective Lagrangian approach. At finite temperature the hadronic masses do not seem to follow a universal scaling law. Considering an exhaustive set of hadronic reactions and vector meson decays we have estimated the photon spectrum emitted from hot hadronic matter taking into account medium effects through thermal loop corrections on the hadronic decay widths and masses. An enhancement in photon emission rate is obtained when we use the in-medium masses of vector mesons in our calculations. It is observed that the effect of p decay width on the photon spectra is negligible.