Extended semiclassical calculations

We propose a method of performing semiclassical calculations using purely real solutions of the classical equations of motion together with Gaussian fluctuations around them. The method has a very close correspondence with recent complex saddle-point calculations, but has certain advantages including ease of computation. For quantum-mechanical problems, the method is shown to give reliable answers in both weak and strong coupling cases, and asymptotically the standard dilute-gas answers are recovered. It directly generalizes to field theories in more than one dimension, and for certain cases all the relevant solutions are already known. 13 references