The likelihood of GODs' existence: improving the SN 1987a constraint on the size of large compact dimensions

The existence of compact dimensions which are accessible only to gravity re presents an intriguing possible solution to the hierarchy problem. At prese nt the strongest constraint on the existence of such compact Gravity-Only D imensions (GODs) comes from SN 1987a. Here we report on the first self-cons istent simulations of the early, neutrino-emitting phase of a proto-neutron star which include energy losses due to the coupling of the Kaluza-Klein m odes of the graviton which arise in a world with GODs. We compare the neutr ino signals from these simulations to that from SN 1987a and use a rigorous probabilistic analysis to derive improved bounds for the radii of such GOD s. We find that the possibility that there are two compact extra dimensions with radii larger than 0.66 mum is excluded at the 95% confidence level - as is the possibility that there are three compact extra dimensions larger than 0.8 nm. (C) 2001 Published by Elsevier Science B.V.