Damping Rate of a Scalar Particle in Hot Scalar QED
  In contrast to the damping of partons in a quark-gluon plasma, the damping of a scalar particle in a hot scalar QED plasma can be calculated to leading order for the whole momentum range using the Braaten-Pisarski method. In this way the evolution of the logarithmic infrared singularity caused by the exchange of a transverse photon from soft to hard momenta can be studied. 
Markus H. Thoma and Christoph T. Traxler