2006/02/22 by Narendra Sahu, Sahu, Narendra
Physics and Astronomy · #Astrophysics (astro-ph) #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #Neutrino Physics Research #Particle physics theoretical and experimental studies #astro-ph #hep-ph
paper · pdf · doi:10.48550/arxiv.hep-ph/0602201
Ph.D thesis (Supervisor: Prof. Urjit A Yajnik), 134 pages
arxiv created 2006/02/22 · openalex publication_date 2006/02/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Baryogenesis via leptogenesis is an attractive scenario that links the physics of right handed neutrino sector with the low energy neutrino data. In the light of current neutrino oscillation data we studied the bound on the mass scale (M1) of lightest right handed neutrino (N1) as well as their mass hierarchy (M2/M1 and M3/M1) from the leptogenesis constraint which we discussed in two different parts of the thesis. In part-I, we studied the canonical leptogenesis in a \it thermal scenario and hence the bound on M1. It is shown that the mass scale of N1 must satisfy the constraint M1≥ 108 GeV in order to produce the adequate lepton asymmetry. We then led to propose a model where this bound can be relaxed to TeV scale. In part-II, we studied the formation and evolution of topological defects which are non-thermal objects and are expected to be formed during the early Universe phase transitions. In particular, we considered B-L cosmic strings and their effect on leptogenesis and hence the bound on the mass scale of N1. It is shown that for the B-L symmetry breaking scale ηB-L>1011GeV, in certain parameter space, the cosmic strings make a more dominant contribution than thermal leptogenesis.