Gravity seminar - Chris Fewster Seminar

Axiomatic approaches to QFT have traditionally been confined to flat (or maximally symmetric) spacetimes, or to the analysis of particular model theories. To go beyond this, it is necessary to understand in general what it means for a theory to represent the same underlying physics in different spacetimes, without assuming the existence of a Lagrangian description. Brunetti, Fredenhagen and Verch (BFV) have proposed a framework for locally covariant QFT, using category theory, that generalizes the axiomatic approach to general curved spacetimes. In this talk, I will review the BFV framework and examine how it can be used to address the question of whether a theory represents the same physics in all spacetimes. I will show that there are theories in the BFV framework that do not have the same physical content in all spacetimes, but propose a condition, called dynamical locality, which removes such pathologies. If time permits, I will also discuss how the BFV framework permits one to analyse the gauge group of a theory. The talk is partly based on recent papers written with Rainer Verch.