Matter-antimatter (a)symmetry in de Sitter Universe

¹ Université de Paris, CNRS, Astroparticule et Cosmologie - F-75013 Paris, France
² Institute of Mathematics and Informatics, Bulgarian Academy of Sciences - Acad. G. Bonchev Str. Bl. 8, 1113, Sofia, Bulgaria

Received: 13 October 2024
Accepted: 20 November 2024

Abstract

We investigate the matter-antimatter properties of elementary systems, modeled as free quantum fields, within the global structure of de Sitter spacetime. By leveraging the distinctive causal and analytic properties of de Sitter spacetime, we propose that matter-antimatter asymmetry could emerge as an observer-dependent effect shaped by time orientation within a local causal patch, rather than as a fundamental property of de Sitter Universe itself. This kinematic perspective complements, rather than replaces, standard dynamical processes —such as baryon number violation, violation, and nonequilibrium processes— that fulfill Sakharov's criteria. Within this framework, the limited presence of antimatter in our predominantly matter-filled Universe, specifically within the causal patch of de Sitter spacetime under consideration, may arise from these mechanisms, though through pathways distinct from conventional interpretations.