Speaker
Description
We review the procedure to construct ground and KMS states, for real scalar fields whose dynamics is dictated by the Klein-Gordon equation, on standard static Lorentzian manifolds with a time-like boundary. We observe that this construction, depending on which boundary condition we fix on the boundary, does not always lead to a bi-distribution $w_2\in \mathcal{D}'(M\times M)$ for the two-point correlation function of the given state. The reason why it fails to be a bi-distribution is the presence of infrared divergences. We discuss an explicit example, namely a real scalar field on Bertotti-Robinson spacetime, proving that infrared divergences occur when Neumann boundary conditions are imposed at the time-like boundary, while for those of Robin-type the underlying two-point correlation function is a well defined bi-distribution of Hadamard form.
