A NEW DIRECT METHOD FOR HEAT KERNEL EXPANSION IN CURVED SPACE AND THE RESUMMED FORM OF NONDERIVATIVE TERM

A new method is proposed for heat kernel expansion in curved space, without using the recursion relation. The existence of the resummed form of nonderivative terms arising out of X from the operator A =-□+ X is proved. The De Witt-Seeley-Gilkey coefficients E₂(x) and E₄(x) are derived.