On global solutions to the semidiscrete stochastic heat equation

We consider the stochastic heat equation on the integer lattice ${\mathbb{Z}}^d$ in dimension $d\ge 3$ and with small coupling constant. We show uniqueness of global solutions within the class of positive functions that are stationary in time and whose asymptotic growth in space is subexponential. Our proof relies on a factorization formula for the point-to-point partition function in the associated polymer model.