Eur. Phys. J. C 19, 183-190
Decay and decoupling of heavy right-handed Majorana neutrinos in the L-R modelParamita Adhya1, D. Rai Chaudhuri1 and Amitava Raychaudhuri2
1 Department of Physics, Presidency College, 86/1, College Street, Calcutta 700073, India
2 Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Calcutta 700009, India
(Received: 1 November 2000 / Published online: 23 February 2001 -© Springer-Verlag 2001)
Heavy right-handed neutrinos are of current interest. The interactions and decay of such neutrinos determine their decoupling epoch during the evolution of the universe. This in turn affects various observable features like the energy density, nucleosynthesis, CMBR spectrum, galaxy formation and baryogenesis. Here, we consider reduction of right-handed electron-type Majorana neutrinos, in the left-right symmetric model, by the WR+WR- channel and the channel originating from an anomaly, involving the SU(2)R gauge group, as well as decay of such neutrinos. We study the reduction of these neutrinos for different ranges of left-right model parameters, and find that, if the neutrino mass exceeds the right-handed gauge boson mass, then the neutrinos never decouple for realistic values of the parameters, but, rather, decay in equilibrium. Because there is no out-of-equilibrium decay, no mass bounds can be set for the neutrinos.
© Società Italiana di Fisica, Springer-Verlag 2001