Solving Solar Neutrino Puzzle via LMA MSW Conversion

Abstract

We analyze the existed solar neutrino experiment data and show the allowed regions. The result from SNO's salt phase itself restricts quite a lot the allowed region's area. Reactor neutrinos play an important role in determining oscillation parameters. KamLAND gives decisive conclusion on the solution to the solar neutrino puzzle, in particular, the spectral distortion in the 766.3 Ty KamLAND data gives another new improvement in the constraint of solar MSW-LMA solutions. We confirm that at 99.73% C.L. the high-LMA solution is excluded. * email: qiuyu@ustc.edu.cn 1 I IntroductionThe electron neutrinos emitted from the sun disappear somewhere when they travel to the earth. This is the famous solar neutrino deficit, which is the almost forty years' "Solar Neutrino Problem".There were many attempts to solve this puzzle during the years. Some of them were tried to modify the solar model in order to give a lower original neutrino flux, which conflict the energy spectrum provided by the 4 first-generation experiments: Homestake, Sage, Gallex and Kamiokande [1,2,3,4]. Recent experiments have shown that the solar neutrino oscillate by ν e → ν µ,τ inside the sun via MSW conversions. This was proven by the Sudbury Neutrino Observatory (SNO) [5], and it was confirmed by the reactor experiment KamLAND [6]. The former experiment detects ν e , ν e + ν µ + ν τ and ν e + 15%(ν µ + ν τ ) three quantities on earth, which correspond to CC, NC and ES interactions respectively; KamLAND observes II Solar neutrinosThe solar neutrino puzzle was solved by the neutrino oscillations ν e → ν µ,τ inside the sun via MSW conversions. This was proved by the Sudbury Neutrino Observatory (SNO) in Canada. And it was confirmed by the laboratory base line experiment KamLAND in Japan.SNO is a 1000 ton heavy water Cerenkov detector mainly measuring 8 B solar neutrinos. It consists of nearly 9450 photon-multiplier tubes and light concentrator units arrayed on a geodesic support structure, with light water surrounding the spherical acrylic vessel containing the D 2 O.The first phase of SNO data is from the pure D 2 O. After that the experimenters add up N aCl (salt) 2 to enhance the NC events rates. This is called the second phase or "salt phase".In analysis of the solar oscillation data [7], we use the χ 2 defined as:where χ 2 1gen stands for Chlorine and Gallium experiments. To calculate each individual chi square in the right hand side of eq. (2.1), we use the so called covariance approach:Here R exp n and R theo n correspond to experimental result and theoretical value for the n-th data point. N=2,34,44 are for χ 2 1gen , χ 2 SK , χ 2 SN O respectively. For getting a R theo n , the important step is to calculate the ν e survival probability. We have used three methods to check its consistency:the Parke formula [8]; the modified semi-analytic formula in [9]; and the completely numerical propagation. We found that the second way is the best, considering both the calculation precision and the computer CPU hour.The covariant matrix of squared ...

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