SEMINAR

Neutrino helicity asymmetries in leptogenesis

Dr. Luís Bento

(CFN - Universidade de Lisboa)

Sala 2.8.3, IST, Edifício Pós-Graduação
Thursday, March 17th, 2005 at 02:00 PM

Abstract

The leptogenesis mechanism is reanalyzed. It is pointed out that the heavy singlet Majorana neutrinos characteristic of leptogenesis possess asymmetries in their abundances contrary to what has been tacitly assumed. Neutrino asymmetries are the differences between abundances of the two helicity states of each neutrino species. They are generated by the same mechanism that generates asymmetries in the standard lepton sector and neutrinos interchange asymmetries with leptons in collisions with each other. A global quantum number, B-L', combining baryon, lepton and neutrino asymmetries, is not violated as fast as the standard B-L, which suppresses the washout effects relevant for the derivation of the final baryon asymmetry. One presents detailed calculations for the period of neutrino thermal production in the framework of the singlet seesaw mechanism.