The neutrino electromagnetic moments and charge radius confront Kamiokande II and Homestake experimental results

Abstract

An analysis is done comparing the main results from the Kamiokande II and chlorine solar neutrino experiments to test the possible existence of a neutrino electric or magnetic moment and charge radius. We find an upper bound on the charge radius of 5.9×10 −11 MeV −2 at 90% CL, an improvement with respect to the previous experimental value by a factor greater than 2. We show that the maximum permissible range for the proper combination of electromagnetic moments has a mild dependence on the theoretical solar model and is reached at the experimental lower bound of the charge radius. Within experimental errors, the apparent discrepancy observed between the data of the two experiments is consistent both with a vanishing magnetic moment and charge radius, and with a Dirac magnetic moment as large as 5.4±1.4×10 −10 μ B for zero charge radius.