Low-energy tests of neutrino masses

Recent solar neutrino and beta decay studies may be revealing the effects of massive neutrinos. Some of the theoretical issues that arise in interpreting solar neutrino, beta decay, and double beta decay experiments are discussed. For instance, what are the relations between the various 'masses' probed in β-decay, neutrino oscillation, and double beta decay experiments? The constraints imposed by the 37Cl, Kamioka II, and 71Ga experiments on solar neutrino oscillations are explored. The author also describes some exotic scenarios that could lead to time variations in the solar neutrino flux