We compute bounce solutions describing false vacuum decay in a ${\Phi }^4$ model in four dimensions with quantum backreaction. The backreaction of the quantum fluctuations on the bounce profiles is computed in the one-loop and Hartree approximations. This is to be compared with the usual semiclassical approach where one computes the profile from the classical action and determines the one-loop correction from this profile. The computation of the fluctuation determinant is performed using a theorem on functional determinants, in addition we here need the Green’s function of the fluctuation operator in oder to compute the quantum backreaction. As we are able to separate from the determinant and from the Gree n’s function the leading perturbative orders, we can regularize and renormalize analytically, in analogy of standard perturbation theory. The iteration towards self-consistent solutions is found to converge for some range of the parameters. Within this range the corrections to the semiclassical action are at most a few percent, the corrections to the transition rate can amount to several orders of magnitude. The strongest deviations happen for large couplings, as to be expected. The transition rates are reduced for the one-loop backreaction, for the Hartree backreaction they are reduced for $\alpha \lesssim 0.5$ and enhanced for larger values of $\alpha$. Beyond some limit, there are no self-consistent bounce solutions.

• Received 3 November 2006

DOI:https://doi.org/10.1103/PhysRevD.75.045001