Topological leptogenesis

In the standard lore, the baryon asymmetry of the present universe is attributed to the leptogenesis from the sterile right-handed neutrino with heavy Majorana fermion mass decaying into the Standard Model's leptons in the very early universe—called the Majorana leptogenesis, while the electroweak sphaleron causes baryogenesis at a later time. In this work, we propose a mechanism, named topological leptogenesis, to explain the lepton asymmetry. Topological leptogenesis replaces some of the sterile neutrinos by introducing a gapped topological order sector (whose low energy exhibits topological quantum field theory with long-range entanglement) that can cancel the baryon minus lepton ( B ± L ) mixed gauge-gravitational anomaly of the standard model . But unlike the Majorana mass gap that causes the continuous ( B − L ) and lepton number L down to the fermion parity Z 2 F , the gapped topological order preserves a discrete ( B ± L ) symmetry, with an extra gauge group over the discrete ( B ± L ) . Then, the beyond-the-standard-model dark matter consists of topological quantum matter, such that the gapped nonparticle excitations of extended line and surface defects with fractionalization and anyon charges can decay into the Standard Model particles. In addition, gravitational leptogenesis can be regarded as an intermediate step (between Majorana particle leptogenesis and topological nonparticle leptogenesis) to mediate such decaying processes from the highly entangled gapped topological order excitations.