Constraints on flavor neutrino masses and sin22θ12 >> sin2θ13 in neutrino oscillations -: art. no. 075011

To realize the condition of sin(2)2 Theta(12)>> sin(2)Theta(13), we find constraints on flavor neutrino masses M-ij (ij=e,mu,tau): (C1) c(23)(2)M(mu mu)+s(23)(2)M(tau tau)approximate to 2s(23)c(23)M(mu tau)+M-ee and/or (C2) vertical bar c(23)M(e mu)-s(23)M(e tau)vertical bar > vertical bar s(23)M(e mu)+c(23)M(e tau)vertical bar, where c(23)=cos Theta(23) (s(23)=sin Theta(23)) and Theta(12), Theta(13), and Theta(23) are the mixing angles for three flavor neutrinos. The applicability of (C1) and (C2) is examined in models with one massless neutrino and two massive neutrinos suggested by det(M)=0, where M is a mass matrix constructed from M-ij (i,j=e,mu,tau). To make definite predictions on neutrino masses and mixings, especially on sin Theta(13), that enable us to trace (C1) and (C2), M is assumed to possess texture zeros or to be constrained by textures with M-mu mu=M-tau tau or M-e tau=+/- M-e mu, which turn out to ensure the emergence of the maximal atmospheric neutrino mixing at sin Theta(13)-> 0. It is found that (C1) is used by textures such as M-e mu=0 or M-e tau=0, while (C2) is used by textures such as M-e tau=+/- M-e mu.