Krein's formula and heat-kernel expansion for some differential operators with a regular singularity
Krein's formula and heat-kernel expansion for some differential operators with a regular singularity
We get a generalization of Krein's formulaâwhich relates the resolvents of different self-adjoint extensions of a differential operator with regular coefficientsâto the non-regular case A = ââ2x + (ν2 â 1/4)/x2 + V(x), where 0 < ν < 1, and V(x) is an analytic function of bounded from below. We âŚ