Acta Physica Polonica B

Vol. 33, No. 2, February 2002, page 641


Fermion Universality Manifesting Itself in the Dirac Component of Neutrino Mass Matrix

Wojciech Krolikowski

An effective texture is presented for six Majorana conventional neutrinos (three active and three sterile), based on a 6\times 6 neutrino mixing matrix whose 3\times 3 active--active component arises from the popular bimaximal mixing matrix of active neutrinos \nu e,  \nu \mu ,  \nu \tau by three small rotations in the 14, 25, 36 planes of \nu 1 , \nu ,  \nu 3 and  \nu 4 , \nu5,  \nu 6 neutrino mass states. The Dirac component (i.e. , 3 \times 3 active-sterile component) of the resulting 6 \times 6 neutrino mass matrix is conjectured to get a structure similar to the charged-lepton and quark 3 \times 3 mass matrices, after the bimaximal mixing, specific for neutrinos, is transformed out unitarily from the neutrino mass matrix. The charged-lepton and quark mass matrices are taken in a universal form constructed previously by the author with a conside- rable phenomenological success. Then, for the option of m21 \simeq m22 \simeq m23 \gg m24 \simeq m25 \simeq m26 \simeq 0, the proposed texture predicts oscillations of solar \nu e's with \Delta m2sol \equiv \Delta m221 \sim  (1.1 to 1.2) \times 10-5   eV2, not inconsistent with the LMA solar solution, if the SuperKamiokande value \Delta m2atm \equiv \Delta m232 \sim  (3 to 3.5) \times 10-3eV2 for oscillations of atmospheric \nu \mu 's is taken as an input. Here, sin2 2\theta sol \sim 1 and sin2 2 \theta atm \sim 1. The texture predicts also an LSND effect with sin2 2\theta LSND  (1.4 to 1.9)\times 10-11  (eV/m1)4 and \Delta m2LSND \equiv \Delta m225 \sim m21 +  (1.1 to 1.2) 10-5\mskip \thickmuskip {eV}2. Unfortunately, the Chooz experiment imposes on the LSND effect (in our texture) a very small upper bound  sin2 2\theta LSND  \lesssim 1.3 \times 10-3, which corresponds to the lower limit m1  \gtsim (1.0 to 1.1)\times 10-2 eV.

PACS numbers: 12.15.Ff, 14.60.Pq, 12.15.Hh


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