Heat kernel asymptotics for Kohn Laplacians on CR manifolds

Abstract

Let $X$ be an abstract orientable not necessarily compact CR manifold of dimension $2n+1$, $n\ge 1$, and let $L^k$ be the $k$-th tensor power of a CR complex line bundle $L$ over $X$. Suppose that condition $Y(q)$ holds at each point of $X$, we establish asymptotics of the heat kernel of Kohn Laplacian with values in $L^k$. As an application, we give a heat kernel proof of Morse inequalities on compact CR manifolds. When $X$ admits a transversal CR $\mathbb{R}$-action, we also establish asymptotics of the $\mathbb{R}$-equivariant heat kernel of Kohn Laplacian with values in $L^k$. As an application, we get $\mathbb{R}$-equivariant Morse inequalities on compact CR manifolds with transversal CR $\mathbb{R}$-action.

42 pages