3 papers
math.DG2026
Formulas for Hadamard coefficients in terms of Green's operators
Lennart Ronge
We describe various ways of obtaining the Hadamard coefficients associated to a normally hyperbolic operator from the corresponding Green's operators. As the Hadamard expansion on…
math.DG2026
A Lorentzian Equivariant Index Theorem
Onirban Islam, Lennart Ronge
We develop a formula for the equivariant index of a twisted Dirac operator on a compact globally hyperbolic spacetime with timelike boundary on which a group acts isometrically, su…
math.DG2025
Perturbations of APS Boundary Conditions for Lorentzian Dirac Operators
Lennart Ronge
We study how far APS boundary conditions for a Lorentzian Dirac operator may be perturbed without destroying Fredholmness of the Dirac operator. This is done by developing criteria…