"Vacuum-like" Hadamard states for quantum fields on curved spacetimes

Marcos Brum, Klaus Fredenhagen
July 01, 2013
We present a modification of the recently proposed Sorkin-Johnston states for scalar free quantum fields on a class of globally hyperbolic spacetimes possessing compact Cauchy hypersurfaces. The modification relies on a smooth cutoff of the commutator function and leads always to Hadamard states, in contrast to the original Sorkin-Johnston states. The modified Sorkin-Johnston states are, however, due to the smoothing no longer uniquely associated to the spacetime.

Hadamard states, quantum fields in curved spacetimes