  A calculation of the bulk viscosity for the massive Gross-Neveu model at zero
fermion chemical potential is presented in the large-$N$ limit. This model
resembles QCD in many important aspects: it is asymptotically free, has a
dynamically generated mass gap, and for zero bare fermion mass it is scale
invariant at the classical level (broken through the trace anomaly at the
quantum level). For our purposes, the introduction of a bare fermion mass is
necessary to break the integrability of the model, and thus to be able to study
momentum transport. The main motivation is, by decreasing the bare mass, to
analyze whether there is a correlation between the maximum in the trace anomaly
and a possible maximum in the bulk viscosity, as recently conjectured. After
numerical analysis, I find that there is no direct correlation between these
two quantities: the bulk viscosity of the model is a monotonously decreasing
function of the temperature. I also comment on the sum rule for the spectral
density in the bulk channel, as well as on implications of this analysis for
other systems.
