  We investigate $\eta/s$ in linear scalar fields modified Gauss-Bonnet theory
that breaks translation invariance. We first calculate $\eta/s$ both
analytically and numerically and show its relationship with temperature in
log-log plot. Our results show that $\eta/s\sim T^2$ at low temperatures. The
causality is also considered in this work. We then find that causality
violation still happens in the presence of the linear scalar field and we
suggest there is a Gauss-Bonnet coupling dependent lower limit for the
effective mass of the graviton. If the effective mass of the graviton is big
enough, then there will be no causality violation and hence no constraints for
the Gauss-Bonnet coupling.
