Violation of C/CP symmetry induced by a scalar field emerging from a two-brane universe: A gateway to baryogenesis

A model of baryogenesis is introduced where our usual visible Universe is a 3-brane coevolving with a hidden 3-brane in a multidimensional bulk. The visible matter and antimatter sectors are naturally coupled with the hidden matter and antimatter sectors, breaking the C/CP invariance and leading to baryogenesis occurring after the quark-gluon era. The issue of leptogenesis is also discussed. The symmetry breaking spontaneously occurs due to the presence of an extra scalar field supported by the U (1 )⊗U (1 ) gauge group, which extends the conventional electromagnetic gauge field in the two-brane universe. Observational consequences are discussed.