Z2 symmetry prediction for the leptonic Dirac CP phase

By S. Ge, D. Dicus, W. Repko. 2011

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Abstract Model-independent consequences of applying a generalized hidden horizontal Z 2 symmetry to the neutrino mass matrix are explored. The Dirac CP phase δ D can be expressed in terms of the three mixing angles as 4 c a s a c s s s s x cos δ D = ( s s 2 − c s 2 s x 2 ) ( c a 2 − s a 2 ) where the s i , c i are sines and cosines of the atmospheric, solar, and reactor angles. This relation is independent of neutrino masses and whether neutrinos are Dirac- or Majorana-type. Given the present constraints on the angles, δ D is constrained to be almost maximal, a result which can be explored in experiments such as NOνA and T2K. The Majorana CP phases do not receive any constraint and are thus model-dependent. Also a distribution of θ x with a lower limit is obtained without specifying δ D .

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/3ea267013d1c59e3048f4439ee496545d0f21296