IMPLICATIONS OF THE GALLEX DETERMINATION OF THE SOLAR NEUTRINO FLUX

The GALLEX result 83 +/- 19 (stat.) +/- 8(syst.) SNU is two standard deviations below the predictions of stellar model calculations (124-132 SNU). To fit this result together with those of the chlorine and Kamiokande experiments requires severe stretching of solar models but does not rule out such a procedure, leaving the possibility of massless neutrinos. It clearly implies that the pp neutrinos have been detected. The Mikheyev-Smirnov-Wolfenstein (MSW) mechanism provides a good fit. and the GALLEX result fixes the DELTA-m2 and sin2 2-theta parameters in two very confined ranges (around DELTA-m2 = 6 x 10(-6)eV2 and sin2 2-theta = 7 x 10(-3) and around DELTA-m2 = 8 X 10(-6)eV2 and sin2 2-theta = 0.6). Explanations of the solar neutrino problem based on the decay or magnetic interactions of neutrinos are disfavoured.