Progress in Nonequilibrium Quantum Field Theory

Abstract

We review recent developments for the description of far-from-equilibrium dynamics of quantum fields and subsequent thermalization.

Figures (11)

• Figure 1: Traces involve a finite closed time path $\mathcal{C}$ suitable for the initial value problem with a causal time evolution.
• Figure 2: The complete NLO contribution to $\Gamma_2$. The dots indicate that each diagram is obtained from the previous one by adding another "rung" with two propagator lines at each vertex. The crosses denote field insertions.
• Figure 3: Two loop contribution to $\Gamma_2$. The solid and dashed lines represent the full fermionic ($D$) and bosonic ($G$) propagators, respectively.
• Figure 4: Comparison of results at LO and at NLO in the 2PI $1/N$-expansion ($N=10$). Left:Equal-time two-point function $F(t,t;p)$ for different momenta as a function of time for "tsunami" initial conditions. Right:Unequal-time two-point function $F(t,0;p=0)$ as a function of time following a sudden "quench". (All in units of the initial-time mass.)
• Figure 5: Comparison between exact (MC) results and results from the 2PI $1/N$--expansion at NLO both for the classical and the quantum field theory. Left: Time evolution of the equal-time correlation function for an initial condition similar as for Fig. \ref{['fig:NLOFM']} with high occupation numbers ($N=4$). Right: Damping rate, extracted from the unequal-time correlation function (cf. Fig. \ref{['fig:NLOFM']}, right). Here the initial conditions are characterized by low occupation numbers so that quantum effects become sizeable.