  We study two observables related to the anomalous breaking of scale
invariance in a dilute two dimensional Fermi gas, the frequency shift and
damping rate of the monopole mode in a harmonic confinement potential. For this
purpose we compute the speed of sound and the bulk viscosity of the two
dimensional gas in the high temperature limit. We show that the anomaly in the
speed of sound scales as $(2P-\rho c_s^2)/P\sim z/[\log(T/E_B)]^2$, and that
the bulk viscosity $\zeta$ scales as $\zeta/\eta \sim z^2/[\log(T/E_B)]^6$.
Here, $P$ is the pressure, $c_s^2$ is the speed of sound, $\eta$ is the shear
viscosity, $z$ is the fugacity, and $E_B$ is the two-body binding energy. We
show that our results are consistent with the experimental results of Vogt et
al. [Phys. Rev. Lett. 108, 070404 (2012)]. Vogt et al. reported a frequency
shift $\delta\omega/\omega$ of the order of a few percent, and a damping rate
smaller than the background rate $\Gamma/\omega_0\sim 5%$.
