## Short-time asymptotics of the heat kernel on a concave boundary.(English)Zbl 0685.58035

From the author’s abstract: A probabilistic method is used to study short-time asymptotic behaviour of heat kernels in the exterior of an insulated smooth convex body. The expansion of the heat kernel p(t,a,b) when both a and b are on the boundary is obtained by reducing the problem to the computation of a Wiener functional on a Brownian bridge. The leading terms of log p(t,a,b) are proved to be $-\frac{\rho^ 2}{2t}- \frac{\mu_ 1\rho^{1/3}}{t^{1/3}}\int^{\rho}_{0}N(s\quad)^{2/3} ds- (\frac{d}{2}+\frac{1}{6})\log t+C_ 0+O(1)$ where $$\rho$$ is the distance between a and b, N(s) is the normal curvature of the geodesic joining a and b, and $$C_ 0$$ is an explicitly identified constant.
Reviewer: N.Jacob

### MSC:

 58J65 Diffusion processes and stochastic analysis on manifolds 35K05 Heat equation
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