On higher derivatives and consistent truncations
James Liu
A consistent truncation is the reduction of a full theory to a subset of its fields such that any solution to the truncated theory will also be a solution to the original theory. Such truncations have been extensively studied in the Kaluza-Klein context, with torus and sphere reductions serving as prime examples. While most of what is known involves truncations of two-derivative theories, I will discuss some preliminary steps towards investigating higher-derivative consistent truncations. The starting point will be the torus reduction of four-derivative heterotic supergravity, which is known to be consistent from a simple zero-mode argument. The actual question of consistency arises from the further removal of the reduced vector multiplets, where I show that the four-derivative couplings present an obstruction to consistent truncations to minimal supergravity in lower dimensions.
