T2K updates its electron-neutrino appearance result using its full dataset obtained by summer 2012

October 23, 2012

The T2K collaboration presented new results on oscillations from muon neutrinos to electron neutrinos at the 2012 International Conference on High Energy Physics in Melbourne, Australia. These oscillations are predicted by quantum physics if neutrinos have non-zero masses. The new results were obtained with more than twice as much data as the T2K paper published in Physical Review Letters in 2011, which announced the first experimental indications for these oscillations.

In Melbourne T2K reported that 11 electron-neutrino events were seen in its far detector Super-Kamiokande, whereas only 3.2 would be expected if there were no oscillations. The probability of these 11 events being due to statistical fluctuations in processes other than oscillations from muon to electron neutrinos is small at 0.08%.

Three separate analyses were made of the T2K data, and gave results that were consistent with each other. The oscillation parameter sin2(2θ13) was measured to be 0.094+0.053-0.040 assuming standard values of related quantities. This parameter represents approximately the fraction of muon neutrinos that oscillate to electron neutrinos when the muon neutrinos have energies of 6 x 108 electron-volts in T2K (one electron-volt is the energy acquired by an electron when it is accelerated in an electric field of one volt).

More details of this result are available on the For Physicists page, and the presentation given at the Melbourne conference is here.