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Stringent neutron-star limits on large extra dimensions

Steen Hannestad, Georg G. Raffelt

hep-pharXiv:hep-ph/0110067

Abstract

Supernovae (SNe) are copious sources for Kaluza-Klein gravitons which are generic for theories with large extra dimensions. These massive particles are produced with average velocities ~0.5 c so that many of them are gravitationally retained by the SN core. Every neutron star thus has a halo of KK gravitons which decay into nu bar-nu, e+e- and gamma gamma on time scales \~109 years. The EGRET gamma-flux limits (Egamma ~ 100 MeV) for nearby neutron stars constrain the fundamental scale for n=2 extra dimensions to M >500 TeV, and M>30 TeV for n=3. The upcoming GLAST satellite is a factor ~30 more sensitive and thus may detect KK decays, for example at the nearby neutron star RX J185635--3754. The requirement that neutron stars are not excessively heated by KK decays implies M>1700 TeV for n=2, and M>60 TeV for n=3.

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