We study the onset of intermittency in stochastic Burgers hydrodynamics, as
characterized by the statistical behavior of negative velocity gradient
fluctuations. The analysis is based on the response functional formalism, where
specific velocity configurations - the viscous instantons - are assumed to play
a dominant role in modeling the left tails of velocity gradient probability
distribution functions. We find, as expected on general grounds, that the field
theoretical approach becomes meaningful in practice only if the effects of
fluctuations around instantons are taken into account. Working with a
systematic cumulant expansion, it turns out that the integration of
fluctuations yields, in leading perturbative order, to an effective description
of the Burgers stochastic dynamics given by the renormalization of its
associated heat kernel propagator and the external force-force correlation
function.Comment: 10 pages, 6 figure
