Analytical description of quasivacuum oscillations of solar neutrinos - art. no. 093002

We propose a simple prescription to calculate the solar neutrino survival p robability P-ee in the quasivacuum oscillation (QVO) regime. Such a prescri ption is obtained by matching perturbative and exact analytical results, wh ich effectively take into account the density distribution in the Sun as pr ovided by the standard solar model. The resulting analytical recipe for the calculation of P-ee is shown to reach its highest accuracy (\DeltaP(ee)\le ss than or equal to2.6 x 10(-2) in the whole QVO range) when the familiar p rescription of choosing the solar density scale parameter r(0) at the Mikhe yev-Smirnov-Wolfenstein (MSW) resonance point is replaced by a new one, nam ely, when, r(0) is chosen at the point of "maximal violation of adiabaticit y" (MVA) along the neutrino trajectory in the Sun. The MVA prescription adm its a smooth transition from the QVO regime to the MSW transition one. We d iscuss in detail the phase acquired by neutrinos in the Sun, and show that it might be of relevance for the studies of relatively short time scale var iations of the fluxes of the solar nu lines in the future real-time solar n eutrino experiments. Finally, we elucidate the role of matter effects in th e convective zone of the Sun.