Non-conservation of global charges in the Brane Universe and baryogenesis

We argue that global charges, such as baryon or lepton number, are not cons erved in theories with the Standard Model fields localized on the brane whi ch propagates in higher-dimensional space-time. The global-charge non-conse rvation is due to quantum fluctuations of the brane surface. These fluctuat ions create "baby branes" that can capture some global charges and carry th em away into the bulk of higher-dimensional space. Such processes are expon entially suppressed at low-energies, but can be significant at high enough temperatures or energies. These effects can lead to a new, intrinsically hi gh-dimensional mechanism of baryogenesis. Baryon asymmetry might be produce d due either to "evaporation" into the baby branes, or creation of the bary on number excess in collisions of two Brane Universes. As an example we dis cuss a possible cosmological scenario within the recently proposed "Brane I nflation" framework. Inflation is driven by displaced branes which slowly f all on top of each other. When the branes collide inflation stops and the B rane Universe reheats. During this non-equilibrium collision baryon number can be transported from one brane to another one. This results in the baryo n number excess in our Universe which exactly equals to the hidden "baryon number" deficit in the other Brane Universe. (C) 1999 Published by Elsevier Science B.V. All rights reserved.