Transits of the QCD critical point

We analyze the evolution of hydrodynamic fluctuations in a heavy-ion collision as the system passes close to the QCD critical point. We introduce two small dimensionless parameters λ and Δs to characterize the evolution. λ compares the microscopic relaxation time (away from the critical point) to the expansion rate λτ0/τQ, and Δs compares the baryon to entropy ratio, n/s, to its critical value, Δs(n/s-nc/sc)/(nc/sc). We determine how the evolution of critical hydrodynamic fluctuations depends parametrically on λ and Δs. Finally, we use this parametric reasoning to estimate the critical fluctuations and correlation length for a heavy-ion collision and to give guidance to the experimental search for the QCD critical point.