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 $U(1)\otimes U(1)$ gauge group, which extends the conventional electromagnetic gauge field in the two-brane universe. Observational consequences are discussed.