abstract

• The NA62 experiment reports the branching ratio measurement BR(K%2b→π%2bνν¯)=(10.6−3.4%2b4.0|stat±0.9syst)×10−11 at 68%25 CL, based on the observation of 20 signal candidates with an expected background of 7.0 events from the total data sample collected at the CERN SPS during 2016–2018. This provides evidence for the very rare K%2b→π%2bνν¯ decay, observed with a significance of 3.4σ. The experiment achieves a single event sensitivity of (0.839 ± 0.054) × 10−11, corresponding to 10.0 events assuming the Standard Model branching ratio of (8.4 ± 1.0) × 10−11. This measurement is also used to set limits on BR(K%2b→ π%2bX), where X is a scalar or pseudo-scalar particle. Details are given of the analysis of the 2018 data sample, which corresponds to about 80%25 of the total data sample. © 2021, The Author(s).

authors

• Aliberti R.
• Ambrosino F.
• Ammendola R.
• Angelucci B.
• Antonelli A.
• Anzivino G.
• Arcidiacono R.
• Bache T.
• Baeva A.
• Baigarashev D.
• Barbanera M.
• Bernhard J.
• Biagioni A.
• Bician L.
• Biino C.
• Bizzeti A.
• Blazek T.
• Bloch-Devaux B.
• Bonaiuto V.
• Boretto M.
• Bragadireanu A.M.
• Britton D.
• Brizioli F.
• Brunetti M.B.
• Bryman D.
• Bucci F.
• Capussela T.
• Carmignani J.
• Ceccucci A.
• Cenci P.
• Cerny V.
• Cerri C.
• Checcucci B.
• Conovaloff A.
• Cooper P.
• Cortina Gil E.
• Corvino M.
• Costantini F.
• Cotta Ramusino A.
• Coward D.
• D'Agostini G.
• Dainton J.
• Dalpiaz P.
• Danielsson H.
• De Simone N.
• Di Filippo D.
• Di Lella L.
• Doble N.
• Duk V.
• Duval F.
• Döbrich B.
• Emelyanov D.
• Engelfried Jatzkowski Jurgen
• Enik T.
• Estrada-Tristan N.
• Falaleev V.
• Fantechi R.
• Fascianelli V.
• Federici L.
• Fedotov S.
• Filippi A.
• Fiorini M.
• Fry J.
• Fu J.
• Fucci A.
• Fulton L.
• Gamberini E.
• Gatignon L.
• Georgiev G.
• Ghinescu S.
• Gianoli A.
• Giorgi M.
• Giudici S.
• Gonnella F.
• Goudzovski E.
• Graham C.
• Guida R.
• Gushchin E.
• Hahn F.
• Heath H.
• Henshaw J.
• Holzer E.B.
• Husek T.
• Hutanu O.E.
• Hutchcroft D.
• Iacobuzio L.
• Iacopini E.
• Imbergamo E.
• Jenninger B.
• Jerhot J.
• Jones R.W.L.
• Kampf K.
• Kekelidze V.
• Kholodenko S.
• Khoriauli G.
• Khotyantsev A.
• Kleimenova A.
• Korotkova A.
• Koval M.
• Kozhuharov V.
• Kucerova Z.
• Kudenko Y.
• Kunze J.
• Kurochka V.
• Kurshetsov V.F.
• Lamanna G.
• Lanfranchi G.
• Lari E.
• Latino G.
• Laycock P.
• Lazzeroni C.
• Lehmann-Miotto G.
• Lenti M.
• Leonardi E.
• Lichard P.
• Litov L.
• Lollini R.
• Lomidze D.
• Lonardo A.
• Lubrano P.
• Lupi M.
• Lurkin N.
• Madigozhin D.
• Mannelli I.
• Mapelli A.
• Marchetto F.
• Marchevski R.
• Martellotti S.
• Massarotti P.
• Massri K.
• Maurice E.
• Medvedeva M.
• Mefodev A.
• Menichetti E.
• Migliore E.
• Minucci E.
• Mirra M.
• Misheva M.
• Molokanova N.
• Moulson M.
• Movchan S.
• Napolitano M.
• Neri I.
• Newson F.
• Norton A.
• Noy M.
• Numao T.
• Obraztsov V.
• Ostankov A.
• Padolski S.
• Page R.
• Palladino V.
• Parenti A.
• Parkinson C.
• Pedreschi E.
• Pepe M.
• Perrin-Terrin M.
• Peruzzo L.
• Petrov P.
• Petrov Y.
• Petrucci F.
• Piandani R.
• Piccini M.
• Pinzino J.
• Polenkevich I.
• Pontisso L.
• Potrebenikov Y.
• Protopopescu D.
• Raggi M.
• Romano A.
• Rubin P.
• Ruggiero G.
• Ryjov V.
• Salamon A.
• Santoni C.
• Saracino G.
• Sargeni F.
• Schuchmann S.
• Semenov V.
• Sergi A.
• Shaikhiev A.
• Shkarovskiy S.
• Soldi D.
• Sozzi M.
• Spadaro T.
• Spinella F.
• Sturgess A.
• Sugonyaev V.
• Swallow J.
• Trilov S.
• Valente P.
• Velghe B.
• Venditti S.
• Vicini P.
• Volpe R.
• Vormstein M.
• Wahl H.
• Wanke R.
• Wrona B.
• Yushchenko O.
• Zamkovsky M.
• Zinchenko A.

publication date

• 2021-01-01

published in

• Journal of High Energy Physics  Journal

keywords

• FCNC Interaction; Fixed target experiments; Flavor physics; Flavour Changing Neutral Currents; Rare decay
• FCNC Interaction; Fixed target experiments; Flavor physics; Flavour Changing Neutral Currents; Rare decay

Digital Object Identifier (DOI)

• 10.1007/JHEP06(2021)093

PubMed ID

start page

end page

volume

• 2021

issue

• 6