Large theta_13 from finite quantum corrections in quasi-degenerate neutrino mass spectrum

We study finite quantum corrections for several well known neutrino mixing matrices and find that it is hard to account for the large value of theta_13 recently reported by T2K and MINOS. To nicely reproduce all experimentally favored neutrino mixing angles and masses, we propose a new neutrino mixing pattern. We also demonstrate a simple realization by slightly extending the standard model to illustrate the quantum corrections.