Speaker
Description
Nearly 30 years since the ADD proposal to solve the hierarchy problem via large extra dimensions, such scenarios have seen a resurgence in interest in the context of the ‘dark dimension’ - an extra dimension of micron scale motivated by the swampland program. We will begin by reviewing the features of the dark dimension, including the possibility that dark matter could consist of Kaluza-Klein gravitons. We will then undertake a systematic study of the model-independent astrophysical constraints on large extra dimensions. These arise from stellar cooling through emission of Kaluza-Klein gravitons. Setting up the calculation from first principles in the context of thermal field theory leads to the identification of a process with no zero-temperature analogue: resonant plasma mixing. After studying a range of previously overlooked processes in red giants, horizontal branch stars, neutron stars, and supernovae, we find that for two or more extra dimensions the leading bounds come from the cooling of supernova 1987A.