Perturbative construction of coherent states

Abstract

The perturbative consistency of coherent states within interacting quantum field theory requires them to be altered beyond the simple nonsqueezed form. Building on this point, we perform explicit construction of consistent squeezed coherent states, required by the finiteness of physical quantities at the one-loop order. Extending this analysis to two loops, we demonstrate that a non-Gaussian alteration of squeezed coherent states is necessary. The modifications of the coherent state we propose are perturbative in ℏ and may be an indication that coherence must be viewed through a nonlinearly redefined, background-dependent, degree of freedom.