First Results from KamLAND: Evidence for Reactor Antineutrino Disappearance

This is the authors' abstract. We don't add key points for this paper.

KamLAND has measured the flux of νₑ's from distant nuclear reactors. We find fewer νₑ events than expected from standard assumptions about νₑ propagation at the 99.95% C.L. In a 162 ton·yr exposure the ratio of the observed inverse β-decay events to the expected number without νₑ disappearance is 0.611±0.085(stat)±0.041(syst) for νₑ energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the ``large mixing angle'' region are excluded.