Abstract
We show that the non-standard neutrino interactions can play a role as subleading effect on the solar neutrino oscillations. We observe that very small flavor universality violations of order of 0.1–0.2 GF is sufficient to induce two phenomena: suppression of the νe-Earth regeneration and a shift of the resonance layer in the Sun. We obtain these phenomena even in the absence of any flavor changing interactions. We discuss their consequences and confront with a global analysis of solar+KamLAND results. We conclude that a new compatibility region in the Δm2×tan2θ⊙, which we call very low large mixing angle region is found for Δm2∼10−5 eV2 and tan2θ⊙=0.45.
Highlights
In the last years, the discovery of neutrino oscillation in solar and reactor experiments selected as a more probable explanation to the solar neutrino problem the so called Large Mixing Angle (LMA) MSW solution
We showed that non-standard neutrino interactions (NSNI) will affect the fit in the LMA region of the MSW solution to the solar neutrino anomaly
When one takes into account the KamLAND results, positive values of the ǫ′ push the allowed region of the neutrino parameters ∆m2 and tan2 θ⊙ at 95% C.L. from pure MSW low-LMA and high-LMA to a completely new region in which ∆m2 is lower than the previous two ones, which we call very-low-LMA
Summary
The discovery of neutrino oscillation in solar and reactor experiments selected as a more probable explanation to the solar neutrino problem the so called Large Mixing Angle (LMA) MSW solution. The SNO [1, 2] and the KamLAND [4] experiments confirm and refine the trend of the evidences of neutrino oscillations due the solar neutrino observations, as measured by Homestake [5], SAGE [6], GALLEX [7], GNO [8] and Super-Kamiokande [9, 10]. The solar oscillation parameters have pinned down to 6 × 10−5 eV2 < ∆m2 < 1 × 10−4 eV2 and 0.3 < tan θ⊙ < 0.55 at 2σ [11]. We assume that non-standard neutrino interactions, which we parameterized by two parameters ǫ′ and ǫ, are present, relaxing the allowed region of the parameters. In the presence of non-standard neutrino interactions, we have found that the allowed interval for ∆m2 increases, rescuing the very low LMA region, ∆m2 ∼ 1 × 10−5 eV2, and the high part of LMA region, ∆m2 ∼ 2 × 10−4 eV2, respectively due the suppression of earth matter and due to a ∆m2 shift induced by a non-zero ǫ′
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