Abstract. We investigate global logarithmic asymptotics of ground states for a family of quantum mean field models. Our approach is based on a stochastic representation and a combination of large deviation and weak KAM techniques. The spin-1 2 case is worked out in more detail.
1.The model and the result 1.1. Introduction. Stochastic representations/path integral approach frequently provides a useful intuition and insight into the structure of quantum spin states. Numerous examples include [2,3,8,10,12,17,18,22,26]. In this work we rely on a path integral approach and related large deviations techniques, and derive global logarithmic asymptotics of ground states for a class of quantum mean field models in transverse field. These asymtotics limits are identified as weak-KAM [16] type solutions of certain Hamilton-Jacobi equations. In principle, such solutions are not unique, and an additional refined analysis along the lines of [14,19,20] is needed for recovering the correct asymptotic ground state. This issue is addressed in more detail for the spin 1 2 -case. In particular, our results imply logarithmic asymptotics of ground states for models with p-body interactions [5]. In the case of Laplacian with periodic potential a weak KAM approach to semiclassical asymptotics was already employed in [1].Our stochastic representation gives rise to a family of continuous time Markov chains on a simplex ∆The transition rates are enhanced by a factor of N , and the chain moves in a potential of the type N F . Ground states are Perron-Frobenius eigenfunctions of the corresponding generators. On the concluding stages of this work we have learned about the series of papers [23][24][25]. The models we consider here essentially fall into a much more general framework studied in these works. The authors of [23][24][25] extend an analysis of Schrödinger operators [14,19,20] on R d to lattice operators on Z d , and they develop powerful techniques, which go well beyond the scope of our work, and which enable a complete asymptotic expansion of low lying eigenvalues and eigenfunctions in neighbourhoods of potential wells. The paper is organized as follows: The class of models is described in Subsection 1.2, and the results are formulated in Subsection 1.4. Main steps of our approach are explained in Section 2, whereas some of the proofs are relegated to Section 3. The