New measurement of $K^{+} \rightarrow \pi^{+}\nu\bar\nu$ branching ratio at the NA62 experiment
R. Fiorenza*,
A. Akmete,
R. Aliberti,
F. Ambrosino,
R. Ammendola,
B. Angelucci,
A. Antonelli, G. Anzivino, R. Arcidiacono, M.U. Ashraf, T. Bache, A. Baeva, D. Baigarashev, L. Bandiera, M. Barbanera, V. Bautin, J. Bernhard, A. Biagioni, L. Bician, C. Biino, A. Bizzeti, T. Blazek, B. Bloch-Devaux, P. Boboc, V. Bonaiuto, M. Boretto, M. Bragadireanu, A. Briano Olvera, D. Britton, F. Brizioli, M.B. Brunetti, D. Bryman, F. Bucci, N. Canale, T. Capussela, J. Carmignani, A. Ceccucci, P. Cenci, M. Ceoletta, V. Cerny, C. Cerri, X. Chang, B. Checcucci, A. Conovaloff, P. Cooper, E. Cortina Gil, M. Corvino, F. Costantini, A. Cotta Ramusino, D. Coward, P. Cretaro, G. D’Agostini, J. Dainton, P. Dalpiaz, H. Danielsson, B. De Martino, M. D’Errico, N. De Simone, D. Di Filippo, L. Di Lella, N. Doble, B. Dobrich, F. Duval, V. Duk, D. Emelyanov, J. Engelfried, T. Enik, N. Estrada-Tristan, V. Falaleev, R. Fantechi, V. Fascianelli, L. Federici, S. Fedotov, A. Filippi, R. Fiorenza, M. Fiorini, M. Francesconi, O. Frezza, J. Fry, J. Fu, A. Fucci, L. Fulton, E. Gamberini, L. Gatignon, G. Georgiev, S. Ghinescu, A. Gianoli, R. Giordano, M. Giorgi, S. Giudici, F. Gonnella, K. Gorshanov, E. Goudzovski, C. Graham, R. Guida, E. Gushchin, F. Hahn, H. Heath, J. Henshaw, Z. Hives, E.B. Holzer, T. Husek, O. Hutanu, D. Hutchcroft, L. Iacobuzio, E. Iacopini, E. Imbergamo, B. Jenninger, J. Jerhot, R.W. Jones, K. Kampf, V. Kekelidze, C. Kenworthy, D. Kereibay, S. Kholodenko, G. Khoriauli, A. Khotyantsev, A. Kleimenova, M. Kolesar, A. Korotkova, M. Koval, V. Kozhuharov, Z. Kucerova, Y. Kudenko, J. Kunze, V. Kurochka, V. Kurshetsov, G. Lanfranchi, G. Lamanna, E. Lari, G. Latino, P. Laycock, C. Lazzeroni, G. Lehmann Miotto, M. Lenti, E. Leonardi, S. Lezki, P. Lichard, L. Litov, P. Lo Chiatto, R. Lollini, D. Lomidze, A. Lonardo, P. Lubrano, M. Lupi, N. Lurkin, D. Madigozhin, I. Mannelli, A. Mapelli, F. Marchetto, R. Marchevski, S. Martellotti, P. Massarotti, K. Massri, E. Maurice, M. Medvedeva, A. Mefodev, E. Menichetti, E. Migliore, E. Minucci, M. Mirra, M. Misheva, N. Molokanova, M. Moulson, S. Movchan, Y. Mukhamejanov, A. Mukhamejanova, M. Napolitano, R. Negrello, I. Neri, F. Newson, A. Norton, M. Noy, T. Numao, V. Obraztsov, A. Okhotnikov, A. Ostankov, S. Padolski, R. Page, V. Palladino, I. Panichi, A. Parenti, C. Parkinson, E. Pedreschi, M. Pepe, M. Perrin-Terrin, L. Peruzzo, L. Petit, P. Petrov, Y. Petrov, F. Petrucci, R. Piandani, M. Piccini, J. Pinzino, L. Plini, I. Polenkevich, C. Polivka, L. Pontisso, Y. Potrebenikov, D. Protopopescu, M. Raggi, M. Reyes Santos, K. Rodriguez Rivera, M. Romagnoni, A. Romano, I. Rosa, P. Rubin, G. Ruggiero, V. Ryjov, A. Sadovskiy, N. Saduyev, S. Sakhiyev, K. Salamatin, A. Salamon, C. Sam, J. Sanders, C. Santoni, G. Saracino, F. Sargeni, J. Schubert, S. Schuchmann, V. Semenov, A. Sergi, A. Shaikhiev, V. Shang, S. Shkarovskiy, M. Soldani, D. Soldi, M. Sozzi, T. Spadaro, F. Spinella, A. Sturgess, V. Sugonyaev, J. Swallow, A. Sytov, G. Tinti, A. Tomczak, S. Trilov, M. Turisini, P. Valente, T. Velas, B. Velghe, S. Venditti, P. Vicini, R. Volpe, M. Vormstein, H. Wahl, R. Wanke, V. Wong, B. Wrona, O. Yushchenko, M. Zamkovsky and A. Zinchenkoet al. (click to show)*: corresponding author
Pre-published on:
December 15, 2025
Published on:
January 28, 2026
Abstract
The $K^{+} \rightarrow \pi^{+}\nu\bar\nu$ decay is a golden mode for flavour physics. Its branching ratio is predicted with
high precision by the Standard Model to be less than $10^{-10}$ , and is highly sensitive to new physics up to the highest mass scales. The NA62 experiment at the CERN SPS, designed to study this
decay, has collected data in 2021–2022 after improvements to the detector. Combining the NA62
datasets collected in 2016–2022, a new measurement $\mathcal B (K^{+} \rightarrow \pi^{+}\nu\bar\nu)$is reported. For the first
time, the $K^{+} \rightarrow \pi^{+}\nu\bar\nu$ decay is observed with a significance exceeding $5\sigma$.
DOI: https://doi.org/10.22323/1.512.0067
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