Observation of νe Appearance (Summer 2013)
The νe appearance analysis was performed on our entire data-set up to April 12th, 2013 (A beam exposure of 6.39×1020 p.o.t.). We observed 28 single-ring electron-like events at Super-Kamiokande while 4.64±0.53 events would be expected if sin2(2θ13) = 0. The probability of background fluctuation resulting in 28 or more events being observed is 9.9×10-14, which, when converted to a significance level, is 7.5σ. The fitted value of sin2(2θ13) is 0.150+0.039-0.034 (0.182+0.046-0.040) assuming δCP = 0, Δm223 = 2.4×10-3 eV2, θ23 = π/4 and normal (inverted) hierarchy. This is the first ever observation of an explicit νe appearance channel.