Hamiltonian formalism for Bose excitations in a plasma with a non-Abelian interaction: plasmon bremsstrahlung

Abstract

The classical Hamiltonian wave theory describing plasmon bremsstrahlung radiation occurring upon collision of high-energy color-charged particles in a hot quark-gluon plasma is proposed. A generalization of the Lie-Poisson bracket to the case of a hot QCD medium, involving two independent components $a^{\phantom{\ast}(1)a}_{\bf k}$ and $a^{\phantom{\ast}(2)a}_{\bf k}$ of the bosonic normal field variable $a^{\phantom{\ast}a}_{\bf k}$ and two non-Abelian color charges $Q^{\,a}_1$ and $Q^{\,a}_2$ is suggested. The canonical transformations including both bosonic degrees of freedom of the soft collective excitations of the hot quark-gluon plasma and degrees of freedom of two hard test particles related to their color charges are written out. The most general structure of the canonical transformations in the form of integro-power series in the components $c^{\phantom{\ast}(\alpha)a}_{\bf k},\,\alpha = 1, 2$, of the new normal field variable $c^{\,a}_{\bf k}$ and in the new color charges ${\mathcal Q}^{a}_{\alpha}$ up to the terms of sixth order is presented. To construct kinetic equations the multiple-time-scale perturbation theory is used. The notion of the plasmon number density ${\mathcal N}^{\,(\alpha,\alpha^{\prime})aa^{\prime}_{\phantom{1}}}_{\bf k}(\tau)$, which is a nontrivial matrix both in the effective color space and in effective two-particle space, is introduced. The self-consistent system of four Boltzmann-type kinetic equations taking into account the time evolution of the averaged color charges of the hard particles is obtained. In the approximation of the fixed color charges of two interacting particles the exact solution of the system of kinetic equations defining the dynamics of the colorless $N^{(1)}_{\bf k}$, $W^{(1)}_{\bf k}$ and color $N^{(2)}_{\bf k}$, $W^{(2)}_{\bf k}$ components of the plasmon number density, is obtained.