Abstract
We consider an effective kinetic description for quantum many-body systems, which is not based on a weak-coupling or diluteness expansion. Instead, it employs an expansion in the number of field components N of the underlying scalar quantum field theory. Extending previous studies, we demonstrate that the large-N kinetic theory at next-to-leading order is able to describe important aspects of highly occupied systems, which are beyond standard perturbative kinetic approaches. We analyze the underlying quasiparticle dynamics by computing the effective scattering matrix elements analytically and solve numerically the large-N kinetic equation for a highly occupied system far from equilibrium. This allows us to compute the universal scaling form of the distribution function at an infrared nonthermal fixed point within a kinetic description and we compare to existing lattice field theory simulation results.
Highlights
A fully microscopic description of the real-time dynamics of quantum many-body systems in terms of quantum field theory can be very demanding
We demonstrate that the large-N kinetic theory at next-to-leading order is able to describe important aspects of highly occupied systems, which are beyond standard perturbative kinetic approaches
We will describe in the following that at next-to-leading order (NLO) in the large-N expansion there is a well-defined effective kinetic description in terms of scatterings between quasiparticles
Summary
A fully microscopic description of the real-time dynamics of quantum many-body systems in terms of quantum field theory can be very demanding. [14,15] and [11,12,13,16] for current perturbative kinetic descriptions) In this situation, typical gauge boson occupancies can become nonperturbatively large at low momenta below the Debye mass scale. Typical gauge boson occupancies can become nonperturbatively large at low momenta below the Debye mass scale These modes may influence the evolution of important quantities like the longitudinal pressure PL of the expanding plasma, evidence of which was found from real-time lattice simulations [17,18,19]. [6,45], it exploits the fact that often one describes complex many-body problems with more than one particle species In this case, alternative kinetic descriptions with an extended range of validity may be derived based on nonperturbative expansions in the number of species available. VIII, we end with two Appendixes on calculational details of the collision integrals (Appendix A) and on integration boundaries (Appendix B)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
