Solar neutrinos and 1-3 leptonic mixing

Effects of the 1-3 leptonic mixing on the solar neutrino observables are studied and the signatures of non-zero θ13 are identified. For this we have re-derived the formula for 3νsurvival probability including all relevant corrections and constructed the iso-contours of observables in the sin θ12−sin θ13 plane. Analysis of the solar neutrino data gives sin θ13 = 0.007 −0.007 (90% C.L.) for ∆m 2 = 8 · 10−5 eV2. The combination of the ratio CC/NC at SNO and gallium production rate selects sin θ13 = 0.017 ± 0.026 (1σ). The global fit of all oscillation data leads to zero best value of sin θ13. The sensitivity (1σ error) of future solar neutrino studies to sin θ13 can be improved down to 0.01 0.02 by precise measurements of the pp-neutrino flux and the CC/NC ratio as well as spectrum distortion at high (E > 4 MeV) energies. Combination of experimental results sensitive to the low and high energy parts of the solar neutrino spectrum resolves the degeneracy of angles θ13 and θ12. Comparison of sin θ13 as well as sin 2 θ12 measured in the solar neutrinos and in the reactor/accelerator experiments may reveal new effects which can not be seen otherwise.