Second Order Corrections to QED Coupling at Low Temperature

We calculate the second order corrections to vacuum polarization tensor of photons at low temperatures, i.e; T $\le 10^{10}$ K ($T << m_e$). The thermal contributions to the QED coupling constant are evaluated at temperatures below the electron mass that is $T< m_e$ . Renormalization of QED at these temperatures has explicitly been checked. The electromagnetic properties of such a thermal medium are modified. Parameters like electric permittivity and magnetic permeability of such a medium are no more constant and become functions of temperature.Comment: 8 latex pages and 1 figure (to appear in IJMP

Two Loop Low Temperature Corrections to Electron Self Energy

We recalculate the two loop corrections in the background heat bath using real time formalism. The procedure of the integrations of loop momenta with dependence on finite temperature before the momenta without it, has been followed. We determine the mass and wavefunction renormalization constants in the low temperature limit of QED, for the first time with this preferred order of integrations. The correction to electron mass and spinors in this limit is important in the early universe at the time of primordial nucleosynthesis as well as in astrophysics.Comment: 8 pages and 1 figure to appear in Chinese Physics

Search for a Signal on QCD Critical Point in Central Nucleus-Nucleus Collisions

We discuss that the QCD critical point could appear in central collisions in percolation cluster. We suggest using the nuclear transparency effect and the one of the light nuclear production to identify the critical point.Comment: To appear in the proceedings of the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (QM2008), Jaipur, India, February 4-10, 200