Measurement of Muon Neutrino Disappearance with the T2K Experiment

Abstract

<p>We describe the measurement of muon neutrino disappearance due to</p><p>neutrino oscillation using the Tokai-2-Kamiokande (T2K) experiment's Run 1-4 (6.57&times;10<super>20</super> POT)</p><p>data set. We analyze the data using the conventional</p><p>Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing</p><p>matrix for the three Standard Model neutrinos. The output of the</p><p>analysis is a measurement of the parameters sin<super>2</super>&theta;₂₃, &Delta;m<super>2</super>₃₂ for the normal hierarchy and sin<super>2</super>&theta;₂₃, &Delta;m<super>2</super>₁₃ for</p><p>the inverted hierarchy. The best-fit oscillation</p><p>parameters for the normal hierarchy are found to be</p><p>(sin<super>2</super>&theta;₂₃, &Delta;m<super>2</super>₃₂) = ( 0.514, 2.51&times;10<super>-3</super> eV<super>2</super>/c<super>4</super>}). The 90% 1D confidence interval -- determined for both parameters</p><p>using the Feldman-Cousins procedure -- is for the normal hierarchy</p><p>0.428 < sin<super>2</super>&theta;₂₃ < 0.598 and</p><p>2.34&times;10<super>-3</super> eV<super>2</super>/c<super>4</super> < &Delta;m<super>2</super>₃₂ < 2.68\times10^{-3} eV<super>2</super>/c<super>4</super>. </p><p>For the inverted hierarchy, the best-fit oscillation parameters are</p><p>(sin<super>2</super>&theta;₂₃, &Delta;m<super>2</super>₁₃) = (0.511, 2.48&times;10<super>-3</super> eV<super>2</super>/c<super>4</super>. The 90\% 1D Feldman-Cousins confidence intervals for the inverted hierarchy are 2.31&times;10<super>-3</super> eV<super>2</super>/c<super>4</super> < \Delta m^2_{13} < 2.64&times;10<super>-3</super> eV<super>2</super>/c<super>4</super>.</p>