After reviewing the soft graviton theorem, we analyze it in arbitrary dimensions under compactification on a circle. This gives the soft behaviours of the graviton, vector and scalar particles in one lower dimensions. For the case of the soft vector field, we also explicitly check the result obtained from compactification by computing the amplitudes with external massive spin-2 and massless finite energy states. The former are the Kaluza-Klein (KK) excitations resulting from the compactification of metric field. Describing the interaction of the KK modes with the vector field at each level by the minimally coupled Fierz-Pauli Lagrangian, we find agreement with the result obtained from compactification, if the gyromagnetic ratio in the minimally coupled Fierz-Pauli action is taken to be g=1.
University of Southampton
Tuesday, December 1, 2020 - 12:00
Online (Microsoft Teams)
Compactification and soft behaviour