First observation of a tau neutrino charged current interaction with charm production in the OPERA experiment

N. Agafonova , A. Aleksandrov , A. Anokhina , S. Aoki , A. Ariga , T. Ariga , A. Bertolin , C. Bozza , R. Brugnera , A. Buonaura , S. Buontempo , M. Chernyavskiy , A. Chukanov , L. Consiglio , N. d'Ambrosio , G. de Lellis , M. de Serio , P. del Amo Sanchez (1) , A. Di Crescenzo , D. Di Ferdinando , N. Di Marco , S. Dmitrievski , M. Dracos (2) , D. Duchesneau (1) , S. Dusini , T. Dzhatdoev , J. Ebert , A. Ereditato , R.A. Fini , F. Fornari , T. Fukuda , G. Galati , A. Garfagnini , V. Gentile , J. Goldberg , S. Gorbunov , Y. Gornushkin , G. Grella , A.M. Guler , C. Gustavino , C. Hagner , T. Hara , T. Hayakawa , A. Hollnagel , K. Ishiguro , A. Iuliano , K. Jakovcic , C. Jollet (2) , C. Kamiscioglu , M. Kamiscioglu , S.H. Kim , N. Kitagawa , B. Klicek , K. Kodama , M. Komatsu , U. Kose , I. Kreslo , F. Laudisio , A. Lauria , A. Longhin , P. Loverre , A. Malgin , M. Malenica , G. Mandrioli , T. Matsuo , V. Matveev , N. Mauri , E. Medinaceli , A. Meregaglia (2) , S. Mikado , M. Miyanishi , F. Mizutani , P. Monacelli , M.C. Montesi , K. Morishima , M.T. Muciaccia , N. Naganawa , T. Naka , M. Nakamura , T. Nakano , K. Niwa , N. Okateva , S. Ogawa , K. Ozaki , A. Paoloni , L. Paparella , B.D. Park , L. Pasqualini , A. Pastore , L. Patrizii , H. Pessard (1) , D. Podgrudkov , N. Polukhina , M. Pozzato , F. Pupilli , M. Roda , T. Roganova , H. Rokujo , G. Rosa , O. Ryazhskaya , O. Sato , A. Schembri , I. Shakirianova , T. Shchedrina , H. Shibuya , E. Shibayama , T. Shiraishi , S. Simone , C. Sirignano , G. Sirri , A. Sotnikov , M. Spinetti , L. Stanco , N. Starkov , S.M. Stellacci , M. Stipcevic , P. Strolin , S. Takahashi , M. Tenti , F. Terranova , V. Tioukov , S. Vasina , P. Vilain , E. Voevodina , L. Votano , J.L. Vuilleumier , G. Wilquet , C.S. Yoon

1 LAPP - Laboratoire d'Annecy de Physique des Particules
2 IPHC - Institut Pluridisciplinaire Hubert Curien

An event topology with two secondary vertices compatible with the decay of short-lived particles was found in the analysis of neutrino interactions in the OPERA target. The observed topology is compatible with tau neutrino charged current (CC) interactions with charm production and neutrino neutral current (NC) interactions with $c\overline{c}$ pair production. However, other processes can mimic this topology. A dedicated analysis was implemented to identify the underlying process. A Monte Carlo simulation was developed and complementary procedures were introduced in the kinematic reconstruction. A multivariate analysis technique was used to achieve an optimal separation of signal from background. Most likely, this event is a $\nu _{\tau }$ CC interaction with charm production, the tau and charm particle decaying into 1 prong and 2 prongs, respectively. The significance of this observation is evaluated.

Mots clés: charm: production; neutrino: interaction; neutrino/tau: particle identification; vertex: secondary; numerical calculations: Monte Carlo; topology; charged current; neutral current; charm: pair production; kinematics; background; statistical analysis; data analysis method; experimental results

Domaines: Physique des Hautes Energies - Expérience [hep-ex]

N. Agafonova, A. Aleksandrov, A. Anokhina, S. Aoki, A. Ariga, et al.. First observation of a tau neutrino charged current interaction with charm production in the OPERA experiment. Eur.Phys.J.C, 2020, 80 (8), pp.699. ⟨10.1140/epjc/s10052-020-8160-y⟩. ⟨hal-02934100⟩