Spectrally cut-off GFF, regularized $Φ^4$ measure, and reflection positivity
We argue that the spectrally cut-off Gaussian free field $Φ_Λ$ on a compact Riemannian manifold or on $\mathbb{R}^n$ cannot satisfy the spatial Markov property. Moreover, when the manifold is reflection positive, we show that $Φ_Λ$ fails to be reflection positive. We explain the difficulties one encounters when trying to deduce the reflection positivity property of the measure exp$(-\|ρΦ_Λ\|_{L^4}^4) μ_{\text{GFF}}(dΦ)$ from the reflection positivity property of the Gaussian free field measure $μ_{\text{GFF}}$ in a naive way. These issues are probably well-known to experts of constructive quantum field theory but to our knowledge, no detailed account can be found in the litterature. Our pedagogical note aims to fill this small gap.
math.PR↗