Nick E. Mavromatos (London):

CPT in the Early Universe and the Observed Baryon Asymmetry

Abstract:

CPT invariance is a property of any relativistic, local and unitary quantum field theory on flat space-times, due to a mathematical theorem. However, in the early Universe the conditions for the validity of the theorem may not all be valid. In the talk I will discuss examples of curved Early-Universe geometries, which lead to apparent CPT Violation of light (active) neutrinos and an induced difference between neutrino/antineutrino populations (a sort of Leptogenesis). The latter can then freeze out at certain conditions and be communicated to the Baryon sector of the Universe, producing a baryon asymmetry of the observed order of magnitude, under natural assumptions.

As explicit examples of such a situation, where the preferential role of neutrinos is singled out, I give early Universe geometries with violations of rotational invariance (and thus Lorentz symmetry) or situations from brane theory, where a brane Universe representing our world passes through a collection of space-time defects in the bulk, represented by appropriately compactified lower-dimensional branes (effective ``D-particles''). If such scenarios turn out to be realistic, then the role of sterile neutrinos on inducing Baryon Asymmetry in the Universe may be obviated.

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