1203.3118 (Shu Luo et al.)

Impacts of the observed theta_13 on the running behaviors of Dirac and
Majorana neutrino mixing angles and CP-violating phases    [PDF]

Shu Luo, Zhi-zhong Xing

The recent Daya Bay observation of the smallest neutrino mixing angle theta_13 poses an important question: can theta_13 \simeq 9^\circ at the electroweak scale be naturally generated from theta_13 = 0^\circ at a superhigh-energy scale via radiative corrections? The answer is negative unless some new degrees of freedom are taken into account, but we find that a relatively large theta_13 may have some nontrivial impacts on the running behaviors of the other two mixing angles and CP-violating phases. We show that the CP-violating phases play a crucial role in the evolution of three mixing angles for both Dirac and Majorana neutrinos, and the sum of three CP-violating phases in the Majorana case is approximately stable against radiative corrections just because theta_13 is not very small. The "correlative" neutrino mixing pattern with theta_12 \simeq 35.3^\circ, theta_23 = 45^\circ and theta_13 \simeq 9.7^\circ, which satisfy the sum rule theta_12 + theta_13 + theta_23 = 90^\circ, is taken as an example to illustrate that the three mixing angles can receive comparably small radiative corrections and thus evolve to their best-fit values at the electroweak scale if the CP-violating phases are properly adjusted.

View original: http://arxiv.org/abs/1203.3118