# Measurement of muon antineutrino oscillations with an accelerator-produced off-axis beam

Abe, K. and Andreopoulos, C. and Antonova, M. and Aoki, S. and Ariga, A. and Assylbekov, S. and Autiero, D. and Barbi, M. and Barker, G. J. and Barr, G. and Bartet-Friburg, P. and Batkiewicz, M. and Bay, F. and Berardi, V. and Berkman, S. and Bhadra, S. and Blondel, A. and Bolognesi, S. and Bordoni, S. and Brailsford, D. and Bravar, A. and Bronner, C. and Avanzini, M. Buizza and Calland, R. G. and Cao, S. and Rodríguez, J. Caravaca and Castillo, R. and Catanesi, M. G. and Cervera, A. and Cherdack, D. and Chikuma, N. and Christodoulou, G. and Coleman, J. and Collazuol, G. and Cremonesi, L. and Dabrowska, A. and Rosa, G. De and Dealtry, T. and Denner, P. F. and Finch, A. J. and Grant, N. and Knox, A. and Kormos, L. L. and Lamont, I. and Lawe, M. and Nowak, J. and O'Keeffe, H. M. and Ratoff, P. N. and Shaw, D. and Southwell, L. (2016) Measurement of muon antineutrino oscillations with an accelerator-produced off-axis beam. Physical review letters, 116 (18). ISSN 1079-7114

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## Abstract

T2K reports its first measurements of the parameters governing the disappearance of $\overline{\nu}_\mu$ in an off-axis beam due to flavour change induced by neutrino oscillations. The quasi-monochromatic $\overline{\nu}_\mu$ beam, produced with a peak energy of 0.6 GeV at J-PARC, is observed at the far detector Super-Kamiokande, 295 km away, where the $\overline{\nu}_\mu$ survival probability is expected to be minimal. Using a dataset corresponding to $4.01 \times 10^{20}$ protons on target, $34$ fully contained $\mu$-like events were observed. The best-fit oscillation parameters are: $\sin^2 (\overline{\theta}_{23}) = 0.45$ and $|\Delta\overline{m}^2_{32}| = 2.51 \times 10^{-3}$ eV$^2$ with 68% confidence intervals of 0.38 - 0.64 and 2.26 - 2.80 ($\times 10^{-3}$ eV$^2$) respectively. These world-leading results are in agreement with existing anti-neutrino parameter measurements and also with the $\nu_\mu$ disappearance parameters measured by T2K.

Item Type:
Journal Article
Journal or Publication Title:
Physical review letters
8 pages, 4 figures
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100
Subjects:
Departments:
ID Code:
78713
Deposited By:
Deposited On:
14 Mar 2016 09:02
Refereed?:
Yes
Published?:
Published