  We present a general analysis of shot noise in an electronic Mach-Zehnder
interferometer, of the type investigated experimentally [Yang Ji et al., Nature
422, 415 (2003)], under the influence of dephasing produced by fluctuations of
a classical field. We show how the usual partition noise expression T(1-T) is
modified by dephasing, depending on the power spectrum of the environmental
fluctuations.
