On string tunneling in power law inflationary universes

Abstract We consider the evolution of circular string loops in power law expanding universes represented by a spatially flat Friedman-Robertson-Walker metric with scale factor a(t) ∝ tp, where t is the cosmic time and p ⩾ 0. Our main result is the existence of a “magic” power p m = 3 + 2 2 . In spacetimes with p