Lorentzian Spectral Geometry for Globally Hyperbolic Surfaces
  The fermionic signature operator is analyzed on globally hyperbolic Lorentzian surfaces. The connection between the spectrum of the fermionic signature operator and geometric properties of the surface is studied. The findings are illustrated by simple examples and counterexamples. 
Felix Finster and Olaf M\"uller
math-ph math.DG math.MP math.SP