Rapidity correlations test stochastic hydrodynamics

We show that measurements of the rapidity dependence of transverse momentum correlations can be used to determine the characteristic time ${\tau }_{\pi }$ that dictates the rate of isotropization of the stress energy tensor, as well as the shear viscosity $\nu =\eta \mathrm{/}sT$. We formulate methods for computing these correlations using second order dissipative hydrodynamics with noise. Current data are consistent with ${\tau }_{\pi }\mathrm{/}\nu \sim 10$ but targeted measurements can improve this precision.