Four-neutrino oscillation solutions of the solar neutrino problem

• Published in: Physical review. D, Particles and fields Particles and fields, 2000-07, Vol.62 (1), Article 013005
• Main Authors: Giunti, C., Gonzalez-Garcia, M. C., Peña-Garay, C.
• Format: Article
• Language: English
• Subjects: Astrofísica nuclear; Collisions (Nuclear physics); Col·lisions (Física nuclear); Neutrins solars; Nuclear astrophysics; Particles (Nuclear physics); Solar neutrinos
• ISSN: 0556-2821; 1089-4918
• DOI: 10.1103/PhysRevD.62.013005

We 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.