Neutrino symmetries from high to low scales

Abstract

Proposed symmetry relations, e.g., quark-lepton complementarity (QLC) or tribimaximal mixing (TBM), need to be imposed at a high scale $\wedge \sim 10^{12}$ GeV characterising the large masses of right-handed neutrinos required to implement the seesaw mechanism. RG evolution down to the laboratory scale $\lambda \sim 10^3$ GeV, generically prone to spoil these relations and their predicted neutrino mixing patterns, can be made to preserve them by appropriately constraining the Majorana phases ${\alpha }_{2,3}$. This is explicitly demonstrated in the MSSM for two versions of QLC and two versions of TBM. A preference for ${\alpha }_2\simeq \pi$ (i.e. $m_1\simeq -m_2$) emerges in each case. Discrimination among the four cases is shown to be possible by future measurements of ${\theta }_{13}$.

Comments: 8 pages, 2 figures. Talk given at the International Workshop on Theoretical and Experimental Physics, IIT (Roorkee), March 2007