Ferromagnetic integrals, correlations and maximum principles. (English) Zbl 0831.35031

Sjöstrand, Johannes

Ann. Inst. Fourier 44, No. 2, 601-628 (1994).

In a previous paper [Astérisque, 210, 303-326 (1992; Zbl 0796.35123)] the author developed an idea of I. M. Singer, B. Wong, S.-T. Yau and S. S.-T. Yau [Ann. Sc. Norm. Super. Pisa, Cl. Sci., IV. Ser. 12, 319-333 (1985; Zbl 0603.35070)] to use the maximum principle in the study of the logarithm of the first eigenfunction of a Schrödinger operator on \(\mathbb{R}^m\) with a strictly convex potential, and for suitable sequences of potentials, he was able to establish the exponential convergence of the first eigenvalue divided by \(m\), when \(m\) tends to infinity. More recently, the reviewer and the author [J. Statistical Phys. 74, No. 1-2, 349-369 (1994)] employed a similar method to study expectation values of the form: \[ \langle f \rangle = \left. \left( \int_{\mathbb{R}^m} \exp - {\varphi (x) \over h} f(x) dx \right) \right/ \int_{\mathbb{R}^m} \exp - {\varphi (x) \over h} dx, \] and in particular the correlations \(({\mathcal C})\) \(\langle (x_j - \langle x_j \rangle) (x_k - \langle x_k \rangle) \rangle\), for large \(m\) and \(|j - k |\). Under suitable assumptions, implying uniform strict convexity for \(\varphi\), it was proved that \(({\mathcal C})\) can be estimated by \({\mathcal O} (1) \exp - |j - k |/C\). In this paper, the author improves the use of the maximum principle and as an application considers for the correlations \(({\mathcal C})\) a critical case and proves power decay upper bounds in terms of the fundamental solution of a certain elliptic operator. In the last part, the author formulates a general maximum principle and gives two applications.

Reviewer: B.Helffer (Orsay)

MSC:

35C20	Asymptotic expansions of solutions to PDEs
81Q10	Selfadjoint operator theory in quantum theory, including spectral analysis
35P15	Estimates of eigenvalues in context of PDEs

Keywords:

exponential convergence of the first eigenvalue; expectation values; maximum principle

Citations:

Zbl 0796.35123; Zbl 0603.35070

References:

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