Global three-neutrino oscillation analysis of neutrino data

Abstract

A global analysis of the solar, atmospheric and reactor neutrino data is presented in terms of three-neutrino oscillations. We include the most recent solar neutrino rates of Homestake, SAGE, GALLEX and GNO, as well as the recent 1117 day Super-Kamiokande data sample, including the recoil electron energy spectrum both for day and night periods, and we treat in a unified way the full parameter space for oscillations, correctly accounting for the transition from the matter enhanced to the vacuum oscillations regime. Likewise, we include in our description conversions with ${\ensuremath{\theta}}_{12}>\ensuremath{\pi}/4.$ For the atmospheric data we perform our analysis of the contained events and the upward-going $\ensuremath{\nu}$-induced muon fluxes, including the previous data samples of Frejus, IMB, Nusex, and Kamioka experiments as well as the full 71 kton yr (1144 days) Super-Kamiokande data set, the recent 5.1 kton yr contained events of Soudan2 and the results on upgoing muons from the MACRO detector. We first present the allowed regions of solar and atmospheric oscillation parameters ${\ensuremath{\theta}}_{12},$ $\ensuremath{\Delta}{m}_{21}^{2}$ and ${\ensuremath{\theta}}_{23},$ $\ensuremath{\Delta}{m}_{32}^{2},$ respectively, as a function of ${\ensuremath{\theta}}_{13}.$ We determine the constraints from atmospheric and solar data on the mixing angle ${\ensuremath{\theta}}_{13},$ common to solar and atmospheric analyses. The solar limit on ${\ensuremath{\theta}}_{13},$ although relatively weak, is totally independent on the allowed range of the atmospheric mass difference $\ensuremath{\Delta}{m}_{32}^{2}.$ On the other hand, the atmospheric data analysis indicates an important complementarity with the reactor limits allowing for a stronger constraint on the allowed value of ${\ensuremath{\theta}}_{13}.$ We also obtain the allowed ranges of parameters from the full five-dimensional combined analysis of the solar, atmospheric and reactor data.