First Oscillation Results for the T2K Experiment

T2K is a long baseline high intensity neutrino oscillation experiment employing an off-axis design to search for the as yet unobserved appearance of \nu_e neutrinos in a \nu_{\mu} beam. The neutrino beam originates at the J-PARC facility in Tokai, Japan and the Super-Kamiokande (SK) detector, located 295 km away, measures the composition of the oscillated beam. The SK data are searched for an excess of \nu_e, constraining the allowed parameter space of sin^2(2\theta_{13}), the parameter governing the amplitude of oscillations from \nu_{\mu} to \nu_e. This amplitude is of particular interest since it also modulates the amplitude of CP violating terms in the lepton mixing matrix. This paper presents results from the first T2K physics run in 2010 with 3.23\times10^19 protons on target.