/ 99 09 20 8 v 2 2 9 M ar 2 00 0 1 Neutrino Mixing in the Seesaw Model
نویسندگان
چکیده
We study the neutrino mixing matrix (the MNS matrix) in the seesaw model. By assuming a large mass hierarchy for the heavy right-handed Majorana mass, we show that, in the diagonal Majorana base, the MNS matrix is determined by a unitary matrix, S, which transforms the neutrino Yukawa matrix, yν , into a triangular form, y△. The mixing matrix of light leptons is VKMS ′∗ , where VKM ≡ VLe VLν and S ′∗ ≡ VLν S. Large mixing may occur without fine tuning of the matrix elements of y△ even if the usual KM-like matrix VKM is given by VKM = 1. This large mixing naturally may satisfy the experimental lower bound of the mixing implied by the atmospheric neutrino oscillation. HUPD-9912
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