New Results from K2K

TL;DR

The K2K experiment observed fewer neutrino events than expected, providing evidence for neutrino oscillations and establishing a method for long-baseline neutrino experiments.

Contribution

This paper reports new experimental results from K2K, demonstrating neutrino oscillations and introducing a methodology for long-baseline neutrino studies.

Findings

Observed 56 neutrino events versus 80.6 expected

Probability of no oscillation is less than 3%

Established a new method for long-baseline experiments

Abstract

During the first half of the K2K run, data corresponding to 4.8x10^19 POT were accumulated. In this data set, 56 accelerator-produced neutrino events were observed in the far detector, while the expected number from the near site measurements is 80.6+7.3-8.0. This means that the probability of the null- oscillation scenario is limited to less than 3%. A method for long-baseline neutrino experiments has been established.