Dynamical evolution of gravitational leptogenesis
- PDF / 989,849 Bytes
- 49 Pages / 595.276 x 841.89 pts (A4) Page_size
- 85 Downloads / 169 Views
Springer
Received: June 25, 2020 Accepted: August 31, 2020 Published: October 5, 2020
Jamie I. McDonalda and Graham M. Shoreb a
Technische Universit¨ at M¨ unchen, Physik-Department, James-Franck-Straße, Garching 85748, Germany b Department of Physics, College of Science, Swansea University, Singleton Park, Swansea SA2 8PP, U.K.
E-mail: [email protected], [email protected] Abstract: Radiatively-induced gravitational leptogenesis is a potential mechanism to explain the observed matter-antimatter asymmetry of the universe. Gravitational tidal effects at the quantum loop level modify the dynamics of the leptons in curved spacetime and may be encoded in a low-energy effective action Seff . It has been shown in previous work how in a high-scale BSM theory the CP odd curvature-induced interactions in Seff modify the dispersion relations of leptons and antileptons differently in an expanding universe, giving rise to an effective chemical potential and a non-vanishing equilibrium lepton-antilepton asymmetry. In this paper, the CP even curvature interactions are shown to break lepton number current conservation and modify the evolution of the lepton number density as the universe expands. These effects are implemented in a generalised Boltzmann equation and used to trace the dynamical evolution of the lepton number density in different cosmological scenarios. The theory predicts a potentially significant gravitationally-induced lepton-antilepton asymmetry at very early times in the evolution of the universe. Keywords: Cosmology of Theories beyond the SM, Effective Field Theories ArXiv ePrint: 2006.09425
c The Authors. Open Access, Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP10(2020)025
JHEP10(2020)025
Dynamical evolution of gravitational leptogenesis
Contents 1 Introduction
1 4 5 7 9 11
3 Effective Lagrangian for gravitational leptogenesis 3.1 Effective Lagrangian 3.2 Weak gravitational field expansion 3.3 Matching conditions
15 15 16 17
4 Lepton number evolution and the Eikonal expansion 4.1 Eikonal expansion for the light neutrinos 4.2 Interpretation in FRW spacetime
18 18 21
5 Gravitational leptogenesis and the extended Boltzmann equation 5.1 Current non-conservation and lepton number evolution 5.2 Gravitational leptogenesis 5.3 Boltzmann equation
22 22 24 25
6 Evolution of gravitational leptogenesis in cosmology 6.1 Radiation-dominated FRW cosmology 6.1.1 Neutrino parameters and the Boltzmann equations 6.1.2 Evolution of the lepton number asymmetry 6.2 Gravitational leptogenesis in the pre-radiation era
29 29 30 34 37
7 Summary and outlook
41
A Analytic results for the Boltzmann equation
43
1
Introduction
The origin of matter-antimatter asymmetry in the universe is one of the most important outstanding issues in cosmology. Radiatively-induced gravitational leptogenesis (RIGL) [1– 3] is a particularly elegant and economical mechanism to generate a lepton number asymmetry in the early universe with the potential to explain the presently observed baryon-tophoton ratio η = (nB
Data Loading...
