We present a new method to prove existence and uniform a priori estimates for Euclidean Gibbs measures corresponding to quantum anharmonic crystals. It is based first on the alternative characterization of Gibbs measures in terms of their logarithmic derivatives through integration by parts formulas, and second on the choice of appropriate Lyapunov functionals.
"Euclidean Gibbs measures on loop lattices: Existence and a priori estimates." Ann. Probab. 32 (1A) 153 - 190, January 2004. https://doi.org/10.1214/aop/1078415832