Effective Mass of the Fröhlich Polaron and the Landau-Pekar-Spohn Conjecture

We prove that there is a constant $\bar{C}\in (0,\mathrm{\infty })$ such that the effective mass $m(\alpha )$ of the Fröhlich Polaron satisfies $m(\alpha )\ge \bar{C}{\alpha }^4$, which is sharp according to a long-standing prediction of Landau-Pekar [19] from 1948 and of Spohn [36] from 1987. The method of proof, which demonstrates how the sharp quartic divergence rate of $m(\alpha )$ appears in a natural way, is based on analyzing the Gaussian representation of the Polaron measure and that of the associated tilted Poisson point process developed in [26]. Additionally, our technique here leads to accompanying results including, 1) an explicit identification of local interval process from [26] in the strong coupling limit in terms of functionals of the Pekar process [27], 2) strict monotonicity of the effective mass $m(\alpha )$ for all $\alpha >0$ and 3) the quartic divergence of $m(\alpha )$ for a generalized class of Polaron type interactions.