Giunti, CarloGonzález García, Ma. ConcepciónPeña Garay, Carlos2010-05-062010-05-0620000556-2821https://hdl.handle.net/2445/12504We present an analysis of the neutrino oscillation solutions of the solar neutrino problem in the framework of four-neutrino mixing where a sterile neutrino is added to the three standard ones. We perform a fit to the full data set corresponding to the 825-day Super-Kamiokande data sample as well as to Chlorine, GALLEX and SAGE and Kamiokande experiments. In our analysis we use all measured total event rates as well as all Super-Kamiokande data on the zenith angle dependence and the recoil electron energy spectrum. We consider both transitions via the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism as well as oscillations in vacuum (just-so) and find the allowed solutions for different values of the additional mixing angles. This framework permits transitions into active or sterile neutrinos controlled by the additional parameter $\cos^2(\vartheta_{23}) \cos^2(\vartheta_{24})$ . We discuss the maximum allowed values of this additional mixing parameter for the different solutions.13 p.application/pdfeng(c) The American Physical Society, 2000Astrofísica nuclearCol·lisions (Física nuclear)Particles (Nuclear physics)Neutrins solarsNuclear astrophysicsCollisions (Nuclear physics)Particles (Nuclear physics)Solar neutrinosinfo:eu-repo/semantics/article551545info:eu-repo/semantics/openAccess