Search for $K^+$ decays to a muon and invisible particles

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">     <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en" xmlns:og="http://ogp.me/ns#" xmlns:fb="http://ogp.me/ns/fb#"> <head> <title>Search for $K^+$ decays to a muon and invisible particles - CERN Document Server</title> <link href='https://framework.web.cern.ch/framework/2.0/fonts/PTSansWeb/PTSansWeb.css' rel='stylesheet' type='text/css' /> <link rel="stylesheet" href="https://cds.cern.ch/img/invenio.css?v=20141127" type="text/css" /> <link rel="stylesheet" href="https://cds.cern.ch/img/cern_theme/css/cern_theme.css?v=20141127" type="text/css" /> <link rel="stylesheet"href="/css/font-awesome.min.css"> <meta http-equiv="X-UA-Compatible" content="IE=Edge"/> <link rel="stylesheet" href="https://cds.cern.ch/img/cern_toolbar/css/toolbar.css" type="text/css" />    <link rel="canonical" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005" /> <link rel="alternate" hreflang="el" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=el" /> <link rel="alternate" hreflang="fr" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=fr" /> <link rel="alternate" hreflang="bg" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=bg" /> <link rel="alternate" hreflang="zh-TW" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=zh_TW" /> <link rel="alternate" hreflang="pt" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=pt" /> <link rel="alternate" hreflang="no" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=no" /> <link rel="alternate" hreflang="hr" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=hr" /> <link rel="alternate" hreflang="ca" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=ca" /> <link rel="alternate" hreflang="de" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=de" /> <link rel="alternate" hreflang="it" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=it" /> <link rel="alternate" hreflang="zh-CN" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=zh_CN" /> <link rel="alternate" hreflang="sv" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=sv" /> <link rel="alternate" hreflang="sk" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=sk" /> <link rel="alternate" hreflang="en" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=en" /> <link rel="alternate" hreflang="pl" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=pl" /> <link rel="alternate" hreflang="ru" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=ru" /> <link rel="alternate" hreflang="ka" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=ka" /> <link rel="alternate" hreflang="ja" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=ja" /> <link rel="alternate" hreflang="es" href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005?ln=es" /> <link rel="alternate" type="application/rss+xml" title="CERN Document Server RSS" href="https://cds.cern.ch/rss" /> <link rel="search" type="application/opensearchdescription+xml" href="https://cds.cern.ch/opensearchdescription" title="CERN Document Server" /> <link rel="unapi-server" type="application/xml" title="unAPI" href="https://cds.cern.ch/unapi" /> <link rel="apple-touch-icon" href="/apple-touch-icon.png"/> <link rel="apple-touch-icon-precomposed" href="/apple-touch-icon-precomposed.png"/> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta http-equiv="Content-Language" content="en" /> <meta name="description" content="The NA62 experiment at CERN reports searches for $K^+\to\mu^+N$ and $K^+\to\mu^+\nu X$ decays, where $N$ and $X$ are massive invisible particles, using the 2016-2018 data set. The $N$ particle is assumed to be a heavy neutral lepton, and the results are expressed as upper limits of ${\cal O}(10^{-8})$ of the neutrino mixing parameter $|U_{\mu4}|^2$ for $N$ masses in the range 200-384 MeV/$c^2$ and lifetime exceeding 50 ns. The $X$ particle is considered a scalar or vector hidden sector mediator decaying to an invisible final state, and upper limits of the decay branching fraction for $X$ masses in the range 10-370 MeV/$c^2$ are reported for the first time, ranging from ${\cal O}(10^{-5})$ to ${\cal O}(10^{-7})$. An improved upper limit of $1.0\times 10^{-6}$ is established at 90% CL on the $K^+\to\mu^+\nu\nu\bar\nu$ branching fraction. The NA62 experiment at CERN reports searches for K+→μ+N and K+→μ+νX decays, where N and X are massive invisible particles, using the 2016–2018 data set. The N particle is assumed to be a heavy neutral lepton, and the results are expressed as upper limits of O(10−8) of the neutrino mixing parameter |Uμ4|2 for N masses in the range 200–384 MeV/ c2 and lifetime exceeding 50 ns. The X particle is considered a scalar or vector hidden sector mediator decaying to an invisible final state, and upper limits of the decay branching fraction for X masses in the range 10–370 MeV/ c2 are reported for the first time, ranging from O(10−5) to O(10−7) . An improved upper limit of 1.0×10−6 is established at 90% CL on the K+→μ+ννν¯ branching fraction. The NA62 experiment at CERN reports searches for $K^+\to\mu^+N$ and $K^+\to\mu^+\nu X$ decays, where $N$ and $X$ are massive invisible particles, using the 2016-2018 data set. The $N$ particle is assumed to be a heavy neutral lepton, and the results are expressed as upper limits of ${\cal O}(10^{-8})$ of the neutrino mixing parameter $|U_{\mu4}|^2$ for $N$ masses in the range 200-384 MeV/$c^2$ and lifetime exceeding 50 ns. The $X$ particle is considered a scalar or vector hidden sector mediator decaying to an invisible final state, and upper limits of the decay branching fraction for $X$ masses in the range 10-370 MeV/$c^2$ are reported for the first time, ranging from ${\cal O}(10^{-5})$ to ${\cal O}(10^{-7})$. An improved upper limit of $1.0\times 10^{-6}$ is established at 90% CL on the $K^+\to\mu^+\nu\nu\bar\nu$ branching fraction. Cortina Gil, Eduardo; Minucci, Elisa; Padolski, Sergey; Petrov, Plamen; Velghe, Bob; Bryman, Douglas; Fu, Ji; Numao, Toshio; Petrov, Yevgeniy; Husek, Tomas; Kampf, Karol; Zamkovsky, Michal; Jerhot, Jan; Aliberti, Riccardo; Khoriauli, Gia; Kunze, Jonas; Lomidze, David; Marchevski, Radoslav; Peruzzo, Letizia; Vormstein, Mario; Wanke, Rainer; Cotta Ramusino, Angelo; Dalpiaz, Pietro; Fiorini, Massimiliano; Gamberini, Enrico; Gianoli, Alberto; Neri, Ilaria; Norton, Alan; Petrucci, Ferruccio; Wahl, Heinrich; Bizzeti, Andrea; Bucci, Francesca; Iacopini, Enrico; Latino, Giuseppe; Lenti, Massimo; Parenti, Andrea; Volpe, Roberta; Antonelli, Antonella; Gonnella, Francesco; Lamanna, Gianluca; Lanfranchi, Gaia; Martellotti, Silvia; Moulson, Matthew; Kozhuharov, Venelin; Litov, Leandar; Georgiev, Georgi; Raggi, Mauro; Spadaro, Tommaso; Ambrosino, Fabio; Capussela, Tiziana; Corvino, Michele; Di Filippo, Domenico; Massarotti, Paolo; Mirra, Marco; Napolitano, Marco; Saracino, Giulio; Anzivino, Giuseppina; Imbergamo, Ermanno; Lollini, Riccardo; Santoni, Cristiano; Brizioli, Francesco; Barbanera, Mattia; Cenci, Patrizia; Checcucci, Bruno; Duk, Viacheslav; Lupi, Matteo; Pepe, Monica; Piccini, Mauro; Lubrano, Pasquale; Costantini, Flavio; Doble, Niels; Giorgi, Marcello; Giudici, Sergio; Lari, Enrico; Pinzino, Jacopo; Pontisso, Luca; Sozzi, Marco; Di Lella, Luigi; Mannelli, Italo; Cerri, Claudio; Fantechi, Riccardo; Pedreschi, Elena; Piandani, Roberto; Spinella, Franco; Biagioni, Andrea; D'Agostini, Giulio; Leonardi, Emanuele; Lonardo, Alessandro; Valente, Paolo; Vicini, Piero; Ammendola, Roberto; Bonaiuto, Vincenzo; De Simone, Nicola; Federici, Luca; Fucci, Adolfo; Salamon, Andrea; Sargeni, Fausto; Arcidiacono, Roberta; Biino, Cristina; Bloch-Devaux, Brigitte; Boretto, Marco; Filippi, Alessandra; Iacobuzio, Lorenza; Marchetto, Flavio; Menichetti, Ezio; Migliore, Ernesto; Soldi, Dario; Engelfried, Jürgen; Estrada-Tristan, Nora; Bragadireanu, Alexandru Mario; Ghinescu, Stefan Alexandru; Hutanu, Ovidiu Emanuel; Enik, Temur; Falaleev, Valeri; Kekelidze, Vladimir; Korotkova, Anna; Madigozhin, Dmitry; Misheva, Milena; Molokanova, Natalia; Movchan, Sergei; Polenkevich, Irina; Potrebenikov, Yuri; Shkarovskiy, Sergey; Zinchenko, Andrey; Baeva, Aigul; Baigarashev, Dosbol; Emelyanov, Dmitry; Fedotov, Sergei; Khotyantsev, Alexey; Gushchin, Evgeny; Kleimenova, Alina; Kudenko, Yury; Kurochka, Viktoriia; Medvedeva, Mariia; Mefodev, Aleksandr; Shaikhiev, Artur; Kholodenko, Sergey; Kurshetsov, Viktor; Obraztsov, Vladimir; Ostankov, Aleksandr; Semenov, Vitali; Sugonyaev, Valentin; Yushchenko, Oleg; Bician, Lubos; Blazek, Tomas; Cerny, Vladimir; Koval, Michal; Kucerova, Zuzana; Ceccucci, Augusto; Bernhard, Johannes; Danielsson, Hans; Döbrich, Babette; Duval, Francois; Gatignon, Lau; Guida, Roberto; Hahn, Ferdinand; Holzer, Eva Barbara; Jenninger, Berthold; Laycock, Paul; Lehmann Miotto, Giovanna; Lichard, Peter; Mapelli, Alessandro; Noy, Matthew; Palladino, Vito; 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(27) </a></li><li class="on"><a href="https://cds.cern.ch/record/2747228/files">Files </a></li></ul> <div id="tabsSpacer" style="clear:both;height:0px"> </div></div> </div> <div class="detailedrecordboxcontent"> <div class="top-left-folded"></div> <div class="top-right-folded"></div> <div class="inside">  <div id="detailedrecordshortreminder"> <div id="clip"> </div> <div id="HB"> <strong><a href="/record/2747228?ln=en">Search for $K^+$ decays to a muon and invisible particles</a></strong> - <a href="/search?f=author&p=Cortina%20Gil%2C%20Eduardo&ln=en">Cortina Gil, Eduardo</a> <em>et al</em> - arXiv:2101.12304CERN-EP-2021-018 </div> </div> <div style="clear:both;height:1px"> </div> <div style="width:90%;margin:auto;min-height:100px;margin-top:10px">  <small><b>Main</b> file(s):</small><ul><table border="0" cellspacing="1" class="searchbox"> <tr> <td align="left" colspan="2" class="portalboxheader"> <img src='https://cds.cern.ch/img/smallfiles.gif' border="0" />  2101.12304 </td> </tr><tr> <td class="portalboxheader"> <font size="-2">version 4<br />(see <a href="https://cds.cern.ch/record/2747228/files/?docname=2101.12304&version=all">previous</a>)</font> </td> <td> <table> <tr> <td valign="top"> <small><a href="https://cds.cern.ch/record/2747228/files/2101.12304.pdf?version=4">2101.12304.pdf</a></small> </td> <td valign="top"> <font size="-2" color="green">[705.11 KB]</font> <font size="-2"><em>31 Jan 2023, 09:17</em> </td> <td valign="top"><em>Fulltext</em></td> </tr></table></td></tr></table><table border="0" cellspacing="1" class="searchbox"> <tr> <td align="left" colspan="2" class="portalboxheader"> <img src='https://cds.cern.ch/img/smallfiles.gif' border="0" />  CERN-EP-2021-018 </td> </tr><tr> <td class="portalboxheader"> <font size="-2">version 2<br />(see <a href="https://cds.cern.ch/record/2747228/files/?docname=CERN-EP-2021-018&version=all">previous</a>)</font> </td> <td> <table> <tr> <td valign="top"> <small><a href="https://cds.cern.ch/record/2747228/files/CERN-EP-2021-018.pdf?version=2">CERN-EP-2021-018.pdf</a></small> </td> <td valign="top"> <font size="-2" color="green">[812.62 KB]</font> <font size="-2"><em>07 Apr 2021, 18:47</em> </td> <td valign="top"><em></em></td> </tr></table></td></tr></table><table border="0" cellspacing="1" class="searchbox"> <tr> <td align="left" colspan="2" class="portalboxheader"> <img src='https://cds.cern.ch/img/smallfiles.gif' border="0" />  scoap3-fulltext </td> </tr><tr> <td class="portalboxheader"> <font size="-2">version 3<br />(see <a href="https://cds.cern.ch/record/2747228/files/?docname=scoap3-fulltext&version=all">previous</a>)</font> </td> <td> <table> <tr> <td valign="top"> <small><a href="https://cds.cern.ch/record/2747228/files/scoap3-fulltext.pdf?version=3">scoap3-fulltext.pdf</a></small> </td> <td valign="top"> <font size="-2" color="green">[578.59 KB]</font> <font size="-2"><em>24 Apr 2021, 06:32</em> </td> <td valign="top"><em>Article from SCOAP3</em></td> </tr></table></td></tr></table></ul><small><b>EPPHAPP_FILE</b> file(s):</small><ul><table border="0" cellspacing="1" class="searchbox"> <tr><td colspan="2" class="restrictedfilerowheader">Restricted</td></tr> <tr> <td align="left" colspan="2" class="portalboxheader"> <img src='https://cds.cern.ch/img/smallfiles.gif' border="0" />  CERN-EP-DRAFT-NA62-2020-005 - draft </td> </tr><tr> <td class="portalboxheader"> <font size="-2">version 3<br />(see <a href="https://cds.cern.ch/record/2747228/files/?docname=CERN-EP-DRAFT-NA62-2020-005%20-%20draft&version=all">previous</a>)</font> </td> <td> <table> <tr> <td valign="top"> <small><a href="https://cds.cern.ch/record/2747228/files/CERN-EP-DRAFT-NA62-2020-005%20-%20draft.pdf?version=3">CERN-EP-DRAFT-NA62-2020-005 - draft.pdf</a></small> </td> <td valign="top"> <font size="-2" color="green">[809.58 KB]</font> <font size="-2"><em>28 Jan 2021, 21:49</em> </td> <td valign="top"><em>Draft (restricted)</em></td> 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