Leptogenesis and tensor polarisation from a gravitational Chern-Simons term
Abstract
Within an effective field theory derived from string theory, the universal axion has to be coupled to the the gravitational Chern-Simons (gCS) term. During any era when the axion field is varying, the vacuum fluctuation of the gravitational wave amplitude will then be circularly polarised, generating an expectation value for the gCS term. The polarisation may be observable through the Cosmic Microwave Background, and the vacuum expectation value of the gCS term may generate the baryon asymmetry of the Universe. We argue here that such effects cannot be computed without further input from string theory, since the `vacuum' in question is unlikely to be the field-theoretic one.
Keywords
Cite
@article{arxiv.hep-th/0501153,
title = {Leptogenesis and tensor polarisation from a gravitational Chern-Simons term},
author = {David H. Lyth and Carlos Quimbay and Yeinzon Rodriguez},
journal= {arXiv preprint arXiv:hep-th/0501153},
year = {2008}
}
Comments
Latex file. 10 pages. v2: Minor changes in the abstract and the conclusion. References added. Version accepted for publication in Journal of High Energy Physics. v3: Typos corrected. Erratum sent for publication