Hamiltonian formalism for Fermi excitations in a plasma with a non-Abelian interaction

TL;DR

This paper develops a Hamiltonian formalism for collective excitations in a high-temperature quark-gluon plasma, incorporating both bosonic and fermionic degrees of freedom, and derives kinetic equations for their interactions.

Contribution

It introduces a generalized Hamiltonian framework for gluon and quark-antiquark excitations in QGP, including canonical transformations and effective Hamiltonians for scattering processes.

Findings

Explicit Hamiltonian for plasmino-plasmino scattering

Derived kinetic equations for elastic scattering in QGP

Comparison with high-temperature QCD matrix elements

Abstract

The Hamiltonian theory for the collective longitudinally polarized colorless gluon excitations (plasmons) and for collective quark-antiquark excitations with abnormal relation between chirality and helicity (plasminos) in a high-temperature quark-gluon plasma (QGP) is developed. For this purpose, Zakharov's forma\-lism for constructing the wave theory in nonlinear media with dispersion is used. A generalization of the Poisson superbracket involving both commuting and anticommuting variables to the case of a continuous medium is performed and the corresponding Hamilton equations are presented. The canonical transformations including simultaneously both bosonic and fermionic degrees of freedom of the collective excitations in QGP are discussed and a complete system of the canonicity conditions for these transformations is written out. An explicit form of the effective fourth-order Hamiltonians describing the elastic scattering of plasmino off plasmino and plasmino off plasmon is found and the Boltzmann type kinetic equations describing the processes of elastic scattering are obtained. A detailed comparison of the effective amplitudes defined within the (pseudo)classical Hamiltonian theory, with the corresponding matrix elements calcu\-la\-ted early in the framework of high-temperature quantum chromodynamics in the so-called hard thermal loop approximation is performed. This enables one to obtain, in particular, an explicit form of the vertex and coefficient functions in the effective amplitudes and in the canonical transformations, correspondingly, and also to define the validity of a purely pseudoclassical approach in the Hamiltonian description of the dynamics of a quark-gluon plasma. The problem of determining the higher-order coefficient functions in the canonical transformations of fermionic and bosonic normal variables is considered.