Absolute Neutrino Masses

where U is the mixing matrix (see Refs. [1–3]). Neutrino oscillations depend on the elements of the mixing matrix U , which determine the amplitude of the oscillations, and on the squared-mass differences ∆m2kj ≡ m 2 k − m 2 j , which determine the oscillation length. The results of solar neutrino experiments (Homestake [4], Kamiokande [5], SAGE [6], GALLEX [7], GNO [8], Super-Kamiokande [9] and SNO [10]) and the reactor long-baseline experiment KamLAND [11] imply that there are large νe → νμ, ντ transitions with a squared-mass difference ∆m 2 SUN ≃ 8× 10 eV. Atmospheric neutrino experiments (Kamiokande [12], IMB [13], SuperKamiokande [14], Soudan-2 [15] and MACRO [16]) and the accelerator K2K