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Measuring the deviation of the 2-3 lepton mixing from maximal with atmospheric neutrinos

The measurement of the deviation of the 2-3 leptonic mixing from maximal, D_23 = 1/2 - sin^2(theta_23), is one of the key issues for understanding the origin of the neutrino masses and mixing. In the three-neutrino context we study the dependence of various observables in the atmospheric neutrinos o...

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Detalles Bibliográficos
Autores principales: González-Garciá, M C, Maltoni, M, Smirnov, A Yu
Lenguaje:eng
Publicado: 2004
Materias:
Acceso en línea:https://dx.doi.org/10.1103/PhysRevD.70.093005
http://cds.cern.ch/record/788897
Descripción
Sumario:The measurement of the deviation of the 2-3 leptonic mixing from maximal, D_23 = 1/2 - sin^2(theta_23), is one of the key issues for understanding the origin of the neutrino masses and mixing. In the three-neutrino context we study the dependence of various observables in the atmospheric neutrinos on D_23. We perform a global three-neutrino analysis of the atmospheric and reactor neutrino data taking into account the effects of both the oscillations driven by the "solar" parameters (Delta_m_21^2 and theta_12) and the 1-3 mixing. The departure from the one-dominant mass scale approximation results into the shift of the 2-3 mixing from maximal by Delta_sin^2(theta_23) ~ 0.04, so that D_23 ~ 0.04 +- 0.07 (1 sigma). Though value of the shift is not statistically significant, the tendency is robust. The shift is induced by the excess of the e-like events in the sub-GeV sample. We show that future large scale water Cherenkov detectors can determine D_23 with accuracy of a few percent, comparable with the sensitivity of future long baseline experiments. Moreover, the atmospheric neutrinos will provide unique information on the sign of the deviation (octant of theta_23).