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<!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>First search for $K^+ \to \pi^0 \pi \mu e$ decays - 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/2899863" /> <link rel="alternate" hreflang="el" href="https://cds.cern.ch/record/2899863?ln=el" /> <link rel="alternate" hreflang="fr" href="https://cds.cern.ch/record/2899863?ln=fr" /> <link rel="alternate" hreflang="bg" href="https://cds.cern.ch/record/2899863?ln=bg" /> <link rel="alternate" hreflang="zh-TW" href="https://cds.cern.ch/record/2899863?ln=zh_TW" /> <link rel="alternate" hreflang="pt" href="https://cds.cern.ch/record/2899863?ln=pt" /> <link rel="alternate" hreflang="no" href="https://cds.cern.ch/record/2899863?ln=no" /> <link rel="alternate" hreflang="hr" href="https://cds.cern.ch/record/2899863?ln=hr" /> <link rel="alternate" hreflang="ca" href="https://cds.cern.ch/record/2899863?ln=ca" /> <link rel="alternate" hreflang="de" href="https://cds.cern.ch/record/2899863?ln=de" /> <link rel="alternate" hreflang="it" href="https://cds.cern.ch/record/2899863?ln=it" /> <link rel="alternate" hreflang="zh-CN" href="https://cds.cern.ch/record/2899863?ln=zh_CN" /> <link rel="alternate" hreflang="sv" href="https://cds.cern.ch/record/2899863?ln=sv" /> <link rel="alternate" hreflang="sk" href="https://cds.cern.ch/record/2899863?ln=sk" /> <link rel="alternate" hreflang="en" href="https://cds.cern.ch/record/2899863?ln=en" /> <link rel="alternate" hreflang="pl" href="https://cds.cern.ch/record/2899863?ln=pl" /> <link rel="alternate" hreflang="ru" href="https://cds.cern.ch/record/2899863?ln=ru" /> <link rel="alternate" hreflang="ka" href="https://cds.cern.ch/record/2899863?ln=ka" /> <link rel="alternate" hreflang="ja" href="https://cds.cern.ch/record/2899863?ln=ja" /> <link rel="alternate" hreflang="es" href="https://cds.cern.ch/record/2899863?ln=es" /> <link rel="alternate" type="application/rss+xml" title="CERN Document Server RSS" href="/rss?ln=en" /> <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 first search for the lepton number violating decay $K^+ \to \pi^0 \pi^- \mu^+ e^+$ and lepton flavour violating decays $K^+ \to \pi^0 \pi^+ \mu^- e^+$, $K^+ \to \pi^0 \pi^+ \mu^+ e^-$ has been performed using a dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of $2.9\times 10^{-10}$, $3.1 \times 10^{-10}$ and $5.0 \times 10^{-10}$, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions. The first search for the lepton number violating decay <math altimg="si1.svg"><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup></math> and lepton flavour violating decays <math altimg="si131.svg"><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup></math>, <math altimg="si132.svg"><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><mo stretchy="false">→</mo><msup><mrow><mi>π</mi></mrow><mrow><mn>0</mn></mrow></msup><msup><mrow><mi>π</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><msup><mrow><mi>μ</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo></mrow></msup></math> has been performed using a dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of <math altimg="si4.svg"><mn>2.9</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo><mn>10</mn></mrow></msup></math>, <math altimg="si5.svg"><mn>3.1</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo><mn>10</mn></mrow></msup></math> and <math altimg="si6.svg"><mn>5.0</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mo linebreak="badbreak" linebreakstyle="after">−</mo><mn>10</mn></mrow></msup></math>, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions. The first search for the lepton number violating decay $K^+\to\pi^0\pi^-\mu^+e^+$ and lepton flavour violating decays $K^+\to\pi^0\pi^+\mu^-e^+$, $K^+\to\pi^0\pi^+\mu^+e^-$ has been performed using a dataset collected by the NA62 experiment at CERN in 2016-2018. Upper limits of $2.9\times 10^{-10}$, $3.1\times 10^{-10}$ and $5.0\times 10^{-10}$, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions. Ashraf, Muhammad Usman; Cortina Gil, Eduardo; Minucci, Elisa; Padolski, Sergey; Petrov, Plamen; Shaikhiev, Artur; Volpe, Roberta; Numao, Toshio; Petrov, Yevgeniy; Velghe, Bob; Wong, Vincent Wai Sum; Bryman, Douglas; Fu, Ji; Hives, Zdenko; Husek, Tomas; Jerhot, Jan; Kampf, Karol; Kolesar, Marian; Zamkovsky, Michal; De Martino, Bianca; Perrin-Terrin, Mathieu; Döbrich, Babette; Lezki, Samet; Schubert, Jonathan; 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; Antonelli, Antonella; Gonnella, Francesco; Lamanna, Gianluca; Lanfranchi, Gaia; Tinti, Gemma; Martellotti, Silvia; Moulson, Matthew; Kozhuharov, Venelin; Litov, Leandar; Georgiev, 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content="Jenninger, Berthold" name="citation_author" /> <meta content="Bautin, Vitalii" name="citation_author" /> <meta content="Cretaro, Paolo" name="citation_author" /> <meta content="D'Agostini, Giulio" name="citation_author" /> <meta content="Schuchmann, Simone" name="citation_author" /> <meta content="Vicini, Piero" name="citation_author" /> <meta content="Lenti, Massimo" name="citation_author" /> <meta content="Koval, Michal" name="citation_author" /> <meta content="Gorshanov, Konstantin" name="citation_author" /> <meta content="Massri, Karim" name="citation_author" /> <meta content="Rubin, Philip David" name="citation_author" /> <meta content="Menichetti, Ezio" name="citation_author" /> <meta content="10.1016/j.physletb.2024.139122" name="citation_doi" /> <meta content="Phys. Lett. B" name="citation_journal_title" /> <meta content="859" name="citation_volume" /> <meta content="139122" name="citation_firstpage" /> <meta content="2024/08/30" name="citation_publication_date" /> <meta name="citation_online_date" content="2024/06/05"> <meta content="CERN-EP-2024-224" name="citation_technical_report_number" /> <meta content="arXiv:2409.12981" name="citation_technical_report_number" /> <meta content="CERN-EP-DRAFT-NA62-2024-001" name="citation_technical_report_institution" /> <meta content="10.1016/j.physletb.2024.139122" name="citation_doi" /> <meta name="citation_pdf_url" content="https://cds.cern.ch/record/2899863/files/CERN-EP-2024-224.pdf" /> <meta name="citation_pdf_url" content="https://cds.cern.ch/record/2899863/files/2409.12981.pdf" /> <meta name="citation_pdf_url" content="https://cds.cern.ch/record/2899863/files/Publication.pdf" />  <meta content="First search for K+ → π0πμe decays" property="og:title" /> <meta content="First search for $K^+ \to \pi^0 \pi \mu e$ decays" property="og:title" /> <meta content="Elsevier B.V." property="og:title" /> <meta content="website" property="og:type" /> <meta content="website" property="og:type" /> <meta content="https://cds.cern.ch/record/2899863" property="og:url" /> <meta name="twitter:image" content="https://cds.cern.ch/record/2899863/files/dp-pim.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/dp-pim.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/dp-pim.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/na62-sketch.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/na62-sketch.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/mass-elm.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/mass-elm.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/mass-pim.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/mass-pim.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/mpiee.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/mpiee.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/mass-mum.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/mass-mum.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/dp-elm.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/dp-elm.png" /> <meta property="og:image" content="https://cds.cern.ch/record/2899863/files/dp-mum.png" /> <meta property="og:image:secure_url" content="https://cds.cern.ch/record/2899863/files/dp-mum.png" /> <meta content="CERN Document Server" property="og:site_name" /> <meta content="Elsevier B.V." property="og:description" /> <meta content="The first search for the lepton number violating decay $K^+ \to \pi^0 \pi^- \mu^+ e^+$ and lepton flavour violating decays $K^+ \to \pi^0 \pi^+ \mu^- e^+$, $K^+ \to \pi^0 \pi^+ \mu^+ e^-$ has been performed using a dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of $2.9\times 10^{-10}$, $3.1 \times 10^{-10}$ and $5.0 \times 10^{-10}$, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions." property="og:description" /> <meta content="arXiv" property="og:description" /> <meta content="The first search for the lepton number violating decay K+→π0π−μ+e+ and lepton flavour violating decays K+→π0π+μ−e+, K+→π0π+μ+e− has been performed using a dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of 2.9×10−10, 3.1×10−10 and 5.0×10−10, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions." property="og:description" /> <meta content="The first search for the lepton number violating decay $K^+\to\pi^0\pi^-\mu^+e^+$ and lepton flavour violating decays $K^+\to\pi^0\pi^+\mu^-e^+$, $K^+\to\pi^0\pi^+\mu^+e^-$ has been performed using a dataset collected by the NA62 experiment at CERN in 2016-2018. Upper limits of $2.9\times 10^{-10}$, $3.1\times 10^{-10}$ and $5.0\times 10^{-10}$, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions." property="og:description" />  <meta content="summary" name="twitter:card" /> <meta content="summary" name="twitter:card" /> <style></style> </head> <body class="NA6232Papers search" lang="en">  <div id="cern-toolbar"> <h1><a href="http://cern.ch" title="CERN">CERN <span>Accelerating science</span></a></h1> <ul> <li class="cern-accountlinks"><a class="cern-account" href="https://cds.cern.ch/youraccount/login?ln=en&referer=https%3A//cds.cern.ch/record/2899863%3Fln%3Den" title="Sign in to your CERN account">Sign in</a></li> <li><a class="cern-directory" href="http://cern.ch/directory" title="Search CERN resources and browse the directory">Directory</a></li> </ul> </div>   <div role="banner" class="clearfix" id="header"> <div class="header-inner inner"> <hgroup class="clearfix"> <h2 id="site-name"> <a rel="home" title="Home" href="/"><span>CERN Document Server</span></a> </h2> <h3 id="site-slogan">Access articles, reports and multimedia content in HEP</h3> </hgroup> <div role="navigation" id="main-navigation" class="cdsmenu"> <h2 class="element-invisible">Main menu</h2><ul class="links inline clearfix"> <li class="menu-386 first active-trail"><a class="active-trail" href="https://cds.cern.ch/?ln=en">Search</a></li> <li class="menu-444 "><a class="" title="" href="https://cds.cern.ch/submit?ln=en">Submit</a></li> <li class="menu-426 "><a class="" href="https://cds.cern.ch/help/?ln=en">Help</a></li> <li class="leaf hassubcdsmenu"> <a hreflang="en" class="header" href="https://cds.cern.ch/youraccount/display?ln=en">Personalize</a> <ul class="subsubcdsmenu"><li><a href="https://cds.cern.ch/youralerts/list?ln=en">Your alerts</a></li><li><a href="https://cds.cern.ch/yourbaskets/display?ln=en">Your baskets</a></li><li><a href="https://cds.cern.ch/yourcomments?ln=en">Your comments</a></li><li><a href="https://cds.cern.ch/youralerts/display?ln=en">Your searches</a></li></ul></li> </ul> </div> </div> </div>  <table class="navtrailbox"> <tr> <td class="navtrailboxbody"> <a href="/?ln=en" class="navtrail">Home</a> > <a href="/collection/CERN%20Experiments?ln=en" class="navtrail">CERN Experiments</a> > <a href="/collection/Fixed%20Target%20Experiments?ln=en" class="navtrail">SPS Experiments</a> > <a href="/collection/NA62?ln=en" class="navtrail">NA62</a> > <a href="/collection/NA62%20Papers?ln=en" class="navtrail">NA62 Papers</a> > First search for $K^+ \to \pi^0 \pi \mu e$ decays </td> </tr> </table> </div> <div class="pagebody"><div class="pagebodystripemiddle"> <div class="detailedrecordbox"> <div class="detailedrecordtabs"> <div> <ul class="detailedrecordtabs"><li class="on first"><a href="/record/2899863/?ln=en">Information </a></li><li class=""><a href="/record/2899863/comments?ln=en">Discussion (4) </a></li><li class=""><a href="/record/2899863/files?ln=en">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">  <abbr class="unapi-id" title="2899863"></abbr>  <link href="/img/download_and_embed_buttons.css" rel="stylesheet" type="text/css" /> <style type="text/css">  .video_talk_wrapper{ max-width: 640px; min-height: 360px; } </style> <table class="formatRecordTableFullWidth"> <tr> <td class="formatRecordHeader" style="background-image: url('/img/journals.jpg');" colspan="2">  Article </td> </tr> <tr><td class="formatRecordLabel"> Report number </td><td style="padding-left:5px;"><a href="http://arxiv.org/abs/arXiv:2409.12981">arXiv:2409.12981</a> ; CERN-EP-2024-224</td></tr> <tr><td class="formatRecordLabel"> Title </td><td style="padding-left:5px;"><b>First search for $K^+ \to \pi^0 \pi \mu e$ decays</b></td></tr> <tr><td class="formatRecordLabel" style="vertical-align:top;">Related title</td><td style="padding-left:5px; ">First search for K+ → π0πμe decays<br/></td></tr> <style> .video_control_container, #video_controlbutton { display: none; }#video_detailbox_download {display: none;}#video_detailbox_embed {display: none;}</style> <div class="video_control_container"> <div style="box-sizing: inherit;position: relative;min-height: 1em;margin: 1em 0;background: #f8f8f9;padding: 1em 1.5em;line-height: 1.4285em;transition: opacity .1s ease,color .1s ease,background .1s ease,box-shadow .1s ease,-webkit-box-shadow .1s ease;border-radius: .28571429rem;font-size: 1.1em;margin-top: 0;margin-bottom: 6px;background-color: #f8ffff;color: #276f86;box-shadow: 0 0 0 1px #a9d5de inset,0 0 0 0 transparent;"> <i class="fa fa-info"></i><span style="padding-left: 9px;">If you experience any problem watching the video, click the download button below</span> </div> <a id="video_controlbutton_download" rel="download_button" class="video_controlbutton" href="#">Download</a> <a id="video_controlbutton_embed" class="video_controlbutton" href="#">Embed</a> </div> <div id="video_detailbox_download" style="margin:10px"> </div> <div id="video_detailbox_embed" style="margin:10px"> </div> <tr><td class="formatRecordLabel"> <span style="white-space:nowrap;">Author(s)</span> </td><td style="padding-left:5px;"> <script type="text/javascript"> function toggle_authors_visibility(){ var more = document.getElementById('more'); var link = document.getElementById('link'); var extension = document.getElementById('extension'); if (more.style.display=='none'){ more.style.display = ''; extension.style.display = 'none'; link.innerHTML = "Hide" } else { more.style.display = 'none'; extension.style.display = ''; link.innerHTML = "Show all 241 authors" } link.style.color = "rgb(204,0,0);" } function set_up(){ var extension = document.getElementById('extension'); extension.innerHTML = "NA62 Collaboration "; toggle_authors_visibility(); } </script> <a name="show_hide" /><p id="more" style=""><a href="https://cds.cern.ch/search?f=author&p=Ashraf%2C%20Muhammad%20Usman&ln=en">Ashraf, Muhammad Usman</a> (Louvain U., CP3) ; <a href="https://cds.cern.ch/search?f=author&p=Cortina%20Gil%2C%20Eduardo&ln=en">Cortina Gil, Eduardo</a> (Louvain U., CP3) ; <a href="https://cds.cern.ch/search?f=author&p=Minucci%2C%20Elisa&ln=en">Minucci, Elisa</a> (Louvain U., CP3 ; Syracuse U.) ; <a href="https://cds.cern.ch/search?f=author&p=Padolski%2C%20Sergey&ln=en">Padolski, Sergey</a> (Louvain U., CP3) ; <a href="https://cds.cern.ch/search?f=author&p=Petrov%2C%20Plamen&ln=en">Petrov, Plamen</a> (Louvain U., CP3) ; <a href="https://cds.cern.ch/search?f=author&p=Shaikhiev%2C%20Artur&ln=en">Shaikhiev, Artur</a> (Louvain U., CP3 ; Lancaster U.) ; <a href="https://cds.cern.ch/search?f=author&p=Volpe%2C%20Roberta&ln=en">Volpe, Roberta</a> (Louvain U., CP3 ; INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Numao%2C%20Toshio&ln=en">Numao, Toshio</a> (TRIUMF) ; <a href="https://cds.cern.ch/search?f=author&p=Petrov%2C%20Yevgeniy&ln=en">Petrov, Yevgeniy</a> (TRIUMF) ; <a href="https://cds.cern.ch/search?f=author&p=Velghe%2C%20Bob&ln=en">Velghe, Bob</a> (TRIUMF) ; <a href="https://cds.cern.ch/search?f=author&p=Wong%2C%20Vincent%20Wai%20Sum&ln=en">Wong, Vincent Wai Sum</a> (TRIUMF) ; <a href="https://cds.cern.ch/search?f=author&p=Bryman%2C%20Douglas&ln=en">Bryman, Douglas</a> (British Columbia U. ; TRIUMF) ; <a href="https://cds.cern.ch/search?f=author&p=Fu%2C%20Ji&ln=en">Fu, Ji</a> (British Columbia U.) ; <a href="https://cds.cern.ch/search?f=author&p=Hives%2C%20Zdenko&ln=en">Hives, Zdenko</a> (Charles U.) ; <a href="https://cds.cern.ch/search?f=author&p=Husek%2C%20Tomas&ln=en">Husek, Tomas</a> (Charles U. ; Birmingham U.) ; <a href="https://cds.cern.ch/search?f=author&p=Jerhot%2C%20Jan&ln=en">Jerhot, Jan</a> (Charles U. ; Munich, Max Planck Inst.) ; <a href="https://cds.cern.ch/search?f=author&p=Kampf%2C%20Karol&ln=en">Kampf, Karol</a> (Charles U.) ; <a href="https://cds.cern.ch/search?f=author&p=Kolesar%2C%20Marian&ln=en">Kolesar, Marian</a> (Charles U.) ; <a href="https://cds.cern.ch/search?f=author&p=Zamkovsky%2C%20Michal&ln=en">Zamkovsky, Michal</a> (Charles U. ; CERN) ; <a href="https://cds.cern.ch/search?f=author&p=De%20Martino%2C%20Bianca&ln=en">De Martino, Bianca</a> (Marseille, CPPM) ; <a href="https://cds.cern.ch/search?f=author&p=Perrin-Terrin%2C%20Mathieu&ln=en">Perrin-Terrin, Mathieu</a> (Marseille, CPPM) ; <a href="https://cds.cern.ch/search?f=author&p=D%C3%B6brich%2C%20Babette&ln=en">Döbrich, Babette</a> (Munich, Max Planck Inst.) ; <a href="https://cds.cern.ch/search?f=author&p=Lezki%2C%20Samet&ln=en">Lezki, Samet</a> (Munich, Max Planck Inst.) ; <a href="https://cds.cern.ch/search?f=author&p=Schubert%2C%20Jonathan&ln=en">Schubert, Jonathan</a> (Munich, Max Planck Inst. ; Tech. U., Munich (main)) ; <a href="https://cds.cern.ch/search?f=author&p=Aliberti%2C%20Riccardo&ln=en">Aliberti, Riccardo</a> (Mainz U., Inst. Phys. ; Helmholtz Inst., Mainz) ; <a href="https://cds.cern.ch/search?f=author&p=Khoriauli%2C%20Gia&ln=en">Khoriauli, Gia</a> (Mainz U., Inst. Phys. ; Wurzburg U.) ; <a href="https://cds.cern.ch/search?f=author&p=Kunze%2C%20Jonas&ln=en">Kunze, Jonas</a> (Mainz U., Inst. Phys.) ; <a href="https://cds.cern.ch/search?f=author&p=Lomidze%2C%20David&ln=en">Lomidze, David</a> (Mainz U., Inst. Phys. ; European XFEL, Hamburg) ; <a href="https://cds.cern.ch/search?f=author&p=Marchevski%2C%20Radoslav&ln=en">Marchevski, Radoslav</a> (EPFL) ; <a href="https://cds.cern.ch/search?f=author&p=Peruzzo%2C%20Letizia&ln=en">Peruzzo, Letizia</a> (Mainz U., Inst. Phys.) ; <a href="https://cds.cern.ch/search?f=author&p=Vormstein%2C%20Mario&ln=en">Vormstein, Mario</a> (Mainz U., Inst. Phys.) ; <a href="https://cds.cern.ch/search?f=author&p=Wanke%2C%20Rainer&ln=en">Wanke, Rainer</a> (Mainz U., Inst. Phys.) ; <a href="https://cds.cern.ch/search?f=author&p=Cotta%20Ramusino%2C%20Angelo&ln=en">Cotta Ramusino, Angelo</a> (INFN, Ferrara) ; <a href="https://cds.cern.ch/search?f=author&p=Dalpiaz%2C%20Pietro&ln=en">Dalpiaz, Pietro</a> (Ferrara U.) ; <a href="https://cds.cern.ch/search?f=author&p=Fiorini%2C%20Massimiliano&ln=en">Fiorini, Massimiliano</a> (Ferrara U.) ; <a href="https://cds.cern.ch/search?f=author&p=Gamberini%2C%20Enrico&ln=en">Gamberini, Enrico</a> (CERN) ; <a href="https://cds.cern.ch/search?f=author&p=Gianoli%2C%20Alberto&ln=en">Gianoli, Alberto</a> (INFN, Ferrara) ; <a href="https://cds.cern.ch/search?f=author&p=Neri%2C%20Ilaria&ln=en">Neri, Ilaria</a> (Ferrara U.) ; <a href="https://cds.cern.ch/search?f=author&p=Norton%2C%20Alan&ln=en">Norton, Alan</a> (Ferrara U. ; Glasgow U.) ; <a href="https://cds.cern.ch/search?f=author&p=Petrucci%2C%20Ferruccio&ln=en">Petrucci, Ferruccio</a> (Ferrara U.) ; <a href="https://cds.cern.ch/search?f=author&p=Wahl%2C%20Heinrich&ln=en">Wahl, Heinrich</a> (Ferrara U. ; Mainz U., Inst. Phys.) ; <a href="https://cds.cern.ch/search?f=author&p=Bizzeti%2C%20Andrea&ln=en">Bizzeti, Andrea</a> (INFN, Florence ; Modena U.) ; <a href="https://cds.cern.ch/search?f=author&p=Bucci%2C%20Francesca&ln=en">Bucci, Francesca</a> (INFN, Florence) ; <a href="https://cds.cern.ch/search?f=author&p=Iacopini%2C%20Enrico&ln=en">Iacopini, Enrico</a> (Florence U.) ; <a href="https://cds.cern.ch/search?f=author&p=Latino%2C%20Giuseppe&ln=en">Latino, Giuseppe</a> (Florence U.) ; <a href="https://cds.cern.ch/search?f=author&p=Lenti%2C%20Massimo&ln=en">Lenti, Massimo</a> (Florence U.) ; <a href="https://cds.cern.ch/search?f=author&p=Parenti%2C%20Andrea&ln=en">Parenti, Andrea</a> (Florence U.) ; <a href="https://cds.cern.ch/search?f=author&p=Antonelli%2C%20Antonella&ln=en">Antonelli, Antonella</a> (Frascati) ; <a href="https://cds.cern.ch/search?f=author&p=Gonnella%2C%20Francesco&ln=en">Gonnella, Francesco</a> (Birmingham U.) ; <a href="https://cds.cern.ch/search?f=author&p=Lamanna%2C%20Gianluca&ln=en">Lamanna, Gianluca</a> (Pisa U.) ; <a href="https://cds.cern.ch/search?f=author&p=Lanfranchi%2C%20Gaia&ln=en">Lanfranchi, Gaia</a> (Frascati) ; <a href="https://cds.cern.ch/search?f=author&p=Tinti%2C%20Gemma&ln=en">Tinti, Gemma</a> (Frascati) ; <a href="https://cds.cern.ch/search?f=author&p=Martellotti%2C%20Silvia&ln=en">Martellotti, Silvia</a> (Frascati) ; <a href="https://cds.cern.ch/search?f=author&p=Moulson%2C%20Matthew&ln=en">Moulson, Matthew</a> (Frascati) ; <a href="https://cds.cern.ch/search?f=author&p=Kozhuharov%2C%20Venelin&ln=en">Kozhuharov, Venelin</a> (Frascati ; Sofiya U.) ; <a href="https://cds.cern.ch/search?f=author&p=Litov%2C%20Leandar&ln=en">Litov, Leandar</a> (Sofiya U.) ; <a href="https://cds.cern.ch/search?f=author&p=Georgiev%2C%20Georgi&ln=en">Georgiev, Georgi</a> (Frascati ; Sofiya U.) ; <a href="https://cds.cern.ch/search?f=author&p=Raggi%2C%20Mauro&ln=en">Raggi, Mauro</a> (Rome U.) ; <a href="https://cds.cern.ch/search?f=author&p=Spadaro%2C%20Tommaso&ln=en">Spadaro, Tommaso</a> (Frascati) ; <a href="https://cds.cern.ch/search?f=author&p=Ambrosino%2C%20Fabio&ln=en">Ambrosino, Fabio</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Fiorenza%2C%20Renato&ln=en">Fiorenza, Renato</a> (Naples U. ; SSM, Naples) ; <a href="https://cds.cern.ch/search?f=author&p=Capussela%2C%20Tiziana&ln=en">Capussela, Tiziana</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Corvino%2C%20Michele&ln=en">Corvino, Michele</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Di%20Filippo%2C%20Domenico&ln=en">Di Filippo, Domenico</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Massarotti%2C%20Paolo&ln=en">Massarotti, Paolo</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Mirra%2C%20Marco&ln=en">Mirra, Marco</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Napolitano%2C%20Marco&ln=en">Napolitano, Marco</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Saracino%2C%20Giulio&ln=en">Saracino, Giulio</a> (Naples U.) ; <a href="https://cds.cern.ch/search?f=author&p=Anzivino%2C%20Giuseppina&ln=en">Anzivino, Giuseppina</a> (Perugia U.) ; <a href="https://cds.cern.ch/search?f=author&p=Imbergamo%2C%20Ermanno&ln=en">Imbergamo, Ermanno</a> (Perugia U.) ; <a href="https://cds.cern.ch/search?f=author&p=Lollini%2C%20Riccardo&ln=en">Lollini, Riccardo</a> (Perugia U.) ; <a href="https://cds.cern.ch/search?f=author&p=Santoni%2C%20Cristiano&ln=en">Santoni, Cristiano</a> (Perugia U.) ; <a href="https://cds.cern.ch/search?f=author&p=Brizioli%2C%20Francesco&ln=en">Brizioli, Francesco</a> (Perugia U. ; CERN) ; <a href="https://cds.cern.ch/search?f=author&p=Barbanera%2C%20Mattia&ln=en">Barbanera, Mattia</a> (INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Cenci%2C%20Patrizia&ln=en">Cenci, Patrizia</a> (INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Checcucci%2C%20Bruno&ln=en">Checcucci, Bruno</a> (INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Duk%2C%20Viacheslav&ln=en">Duk, Viacheslav</a> (Birmingham U. ; INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Lupi%2C%20Matteo&ln=en">Lupi, Matteo</a> (INFN, Perugia ; Goethe U., Frankfurt, Inst. Inform.) ; <a href="https://cds.cern.ch/search?f=author&p=Pepe%2C%20Monica&ln=en">Pepe, Monica</a> (INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Piccini%2C%20Mauro&ln=en">Piccini, Mauro</a> (INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Lubrano%2C%20Pasquale&ln=en">Lubrano, Pasquale</a> (INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Costantini%2C%20Flavio&ln=en">Costantini, Flavio</a> (Pisa U.) ; <a href="https://cds.cern.ch/search?f=author&p=Doble%2C%20Niels&ln=en">Doble, Niels</a> (Pisa U. ; Mainz U., Inst. Phys.) ; <a href="https://cds.cern.ch/search?f=author&p=Giorgi%2C%20Marcello&ln=en">Giorgi, Marcello</a> (Pisa U.) ; <a href="https://cds.cern.ch/search?f=author&p=Giudici%2C%20Sergio&ln=en">Giudici, Sergio</a> (Pisa U.) ; <a href="https://cds.cern.ch/search?f=author&p=Lari%2C%20Enrico&ln=en">Lari, Enrico</a> (Pisa U.) ; <a href="https://cds.cern.ch/search?f=author&p=Pinzino%2C%20Jacopo&ln=en">Pinzino, Jacopo</a> (CERN ; INFN, Pisa) ; <a href="https://cds.cern.ch/search?f=author&p=Pontisso%2C%20Luca&ln=en">Pontisso, Luca</a> (INFN, Pisa ; INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Sozzi%2C%20Marco&ln=en">Sozzi, Marco</a> (Pisa U.) ; <a href="https://cds.cern.ch/search?f=author&p=Di%20Lella%2C%20Luigi&ln=en">Di Lella, Luigi</a> (Pisa U. ; Mainz U., Inst. Phys.) ; <a href="https://cds.cern.ch/search?f=author&p=Mannelli%2C%20Italo&ln=en">Mannelli, Italo</a> (Pisa, Scuola Normale Superiore) ; <a href="https://cds.cern.ch/search?f=author&p=Cerri%2C%20Claudio&ln=en">Cerri, Claudio</a> (INFN, Pisa) ; <a href="https://cds.cern.ch/search?f=author&p=Fantechi%2C%20Riccardo&ln=en">Fantechi, Riccardo</a> (INFN, Pisa) ; <a href="https://cds.cern.ch/search?f=author&p=Pedreschi%2C%20Elena&ln=en">Pedreschi, Elena</a> (Pisa U.) ; <a href="https://cds.cern.ch/search?f=author&p=Piandani%2C%20Roberto&ln=en">Piandani, Roberto</a> (Perugia U. ; San Luis Potosi U.) ; <a href="https://cds.cern.ch/search?f=author&p=Spinella%2C%20Franco&ln=en">Spinella, Franco</a> (INFN, Pisa) ; <a href="https://cds.cern.ch/search?f=author&p=Biagioni%2C%20Andrea&ln=en">Biagioni, Andrea</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=D%27Agostini%2C%20Giulio&ln=en">D'Agostini, Giulio</a> (Rome U.) ; <a href="https://cds.cern.ch/search?f=author&p=Leonardi%2C%20Emanuele&ln=en">Leonardi, Emanuele</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Lonardo%2C%20Alessandro&ln=en">Lonardo, Alessandro</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Valente%2C%20Paolo&ln=en">Valente, Paolo</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Vicini%2C%20Piero&ln=en">Vicini, Piero</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Cretaro%2C%20Paolo&ln=en">Cretaro, Paolo</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Turisini%2C%20Matteo&ln=en">Turisini, Matteo</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Frezza%2C%20Ottorino&ln=en">Frezza, Ottorino</a> (INFN, Rome) ; <a href="https://cds.cern.ch/search?f=author&p=Ammendola%2C%20Roberto&ln=en">Ammendola, Roberto</a> (Rome U., Tor Vergata) ; <a href="https://cds.cern.ch/search?f=author&p=Bonaiuto%2C%20Vincenzo&ln=en">Bonaiuto, Vincenzo</a> (Rome U., Tor Vergata) ; <a href="https://cds.cern.ch/search?f=author&p=De%20Simone%2C%20Nicola&ln=en">De Simone, Nicola</a> (CERN ; DESY) ; <a href="https://cds.cern.ch/search?f=author&p=Federici%2C%20Luca&ln=en">Federici, Luca</a> (CERN) ; <a href="https://cds.cern.ch/search?f=author&p=Fucci%2C%20Adolfo&ln=en">Fucci, Adolfo</a> (Rome U., Tor Vergata) ; <a href="https://cds.cern.ch/search?f=author&p=Salamon%2C%20Andrea&ln=en">Salamon, Andrea</a> (Rome U., Tor Vergata) ; <a href="https://cds.cern.ch/search?f=author&p=Sargeni%2C%20Fausto&ln=en">Sargeni, Fausto</a> (Rome U., Tor Vergata) ; <a href="https://cds.cern.ch/search?f=author&p=Arcidiacono%2C%20Roberta&ln=en">Arcidiacono, Roberta</a> (Turin U. ; Piemonte Orientale U., Novara) ; <a href="https://cds.cern.ch/search?f=author&p=Biino%2C%20Cristina&ln=en">Biino, Cristina</a> (INFN, Turin) ; <a href="https://cds.cern.ch/search?f=author&p=Bloch-Devaux%2C%20Brigitte&ln=en">Bloch-Devaux, Brigitte</a> (Turin U. ; Louvain U., CP3 ; Birmingham U.) ; <a href="https://cds.cern.ch/search?f=author&p=Boretto%2C%20Marco&ln=en">Boretto, Marco</a> (Turin U. ; CERN) ; <a href="https://cds.cern.ch/search?f=author&p=Filippi%2C%20Alessandra&ln=en">Filippi, Alessandra</a> (INFN, Turin) ; <a href="https://cds.cern.ch/search?f=author&p=Iacobuzio%2C%20Lorenza&ln=en">Iacobuzio, Lorenza</a> (Birmingham U.) ; <a href="https://cds.cern.ch/search?f=author&p=Marchetto%2C%20Flavio&ln=en">Marchetto, Flavio</a> (INFN, Turin) ; <a href="https://cds.cern.ch/search?f=author&p=Menichetti%2C%20Ezio&ln=en">Menichetti, Ezio</a> (Turin U.) ; <a href="https://cds.cern.ch/search?f=author&p=Migliore%2C%20Ernesto&ln=en">Migliore, Ernesto</a> (Turin U.) ; <a href="https://cds.cern.ch/search?f=author&p=Soldi%2C%20Dario&ln=en">Soldi, Dario</a> (Turin U.) ; <a href="https://cds.cern.ch/search?f=author&p=Engelfried%2C%20J%C3%BCrgen&ln=en">Engelfried, Jürgen</a> (San Luis Potosi U.) ; <a href="https://cds.cern.ch/search?f=author&p=Estrada-Tristan%2C%20Nora&ln=en">Estrada-Tristan, Nora</a> (San Luis Potosi U. ; Guanajuato U.) ; <a href="https://cds.cern.ch/search?f=author&p=Bragadireanu%2C%20Alexandru%20Mario&ln=en">Bragadireanu, Alexandru Mario</a> (Bucharest, IFIN-HH) ; <a href="https://cds.cern.ch/search?f=author&p=Ghinescu%2C%20Stefan%20Alexandru&ln=en">Ghinescu, Stefan Alexandru</a> (Bucharest, IFIN-HH) ; <a href="https://cds.cern.ch/search?f=author&p=Hutanu%2C%20Ovidiu%20Emanuel&ln=en">Hutanu, Ovidiu Emanuel</a> (Bucharest, IFIN-HH) ; <a href="https://cds.cern.ch/search?f=author&p=Enik%2C%20Temur&ln=en">Enik, Temur</a> ; <a href="https://cds.cern.ch/search?f=author&p=Falaleev%2C%20Valeri&ln=en">Falaleev, Valeri</a> (INFN, Perugia) ; <a href="https://cds.cern.ch/search?f=author&p=Kekelidze%2C%20Vladimir&ln=en">Kekelidze, Vladimir</a> ; <a href="https://cds.cern.ch/search?f=author&p=Korotkova%2C%20Anna&ln=en">Korotkova, Anna</a> ; <a href="https://cds.cern.ch/search?f=author&p=Madigozhin%2C%20Dmitry&ln=en">Madigozhin, Dmitry</a> ; <a href="https://cds.cern.ch/search?f=author&p=Misheva%2C%20Milena&ln=en">Misheva, Milena</a> (Sofiya, Inst. Nucl. Res.) ; <a href="https://cds.cern.ch/search?f=author&p=Molokanova%2C%20Natalia&ln=en">Molokanova, Natalia</a> ; <a href="https://cds.cern.ch/search?f=author&p=Movchan%2C%20Sergei&ln=en">Movchan, Sergei</a> ; <a href="https://cds.cern.ch/search?f=author&p=Polenkevich%2C%20Irina&ln=en">Polenkevich, Irina</a> ; <a href="https://cds.cern.ch/search?f=author&p=Potrebenikov%2C%20Yuri&ln=en">Potrebenikov, Yuri</a> ; <a href="https://cds.cern.ch/search?f=author&p=Shkarovskiy%2C%20Sergey&ln=en">Shkarovskiy, Sergey</a> ; <a href="https://cds.cern.ch/search?f=author&p=Zinchenko%2C%20Andrey&ln=en">Zinchenko, Andrey</a> ; <a href="https://cds.cern.ch/search?f=author&p=Baeva%2C%20Aigul&ln=en">Baeva, Aigul</a> ; <a href="https://cds.cern.ch/search?f=author&p=Baigarashev%2C%20Dosbol&ln=en">Baigarashev, Dosbol</a> (Eurasian Nat. U., Astana) ; <a href="https://cds.cern.ch/search?f=author&p=Emelyanov%2C%20Dmitry&ln=en">Emelyanov, Dmitry</a> ; <a href="https://cds.cern.ch/search?f=author&p=Fedotov%2C%20Sergei&ln=en">Fedotov, Sergei</a> ; <a href="https://cds.cern.ch/search?f=author&p=Khotyantsev%2C%20Alexey&ln=en">Khotyantsev, Alexey</a> ; <a href="https://cds.cern.ch/search?f=author&p=Gushchin%2C%20Evgeny&ln=en">Gushchin, Evgeny</a> ; <a href="https://cds.cern.ch/search?f=author&p=Kleimenova%2C%20Alina&ln=en">Kleimenova, Alina</a> (EPFL) ; <a href="https://cds.cern.ch/search?f=author&p=Kudenko%2C%20Yury&ln=en">Kudenko, Yury</a> ; <a href="https://cds.cern.ch/search?f=author&p=Kurochka%2C%20Viktoriia&ln=en">Kurochka, Viktoriia</a> ; <a href="https://cds.cern.ch/search?f=author&p=Medvedeva%2C%20Mariia&ln=en">Medvedeva, Mariia</a> ; <a href="https://cds.cern.ch/search?f=author&p=Mefodev%2C%20Aleksandr&ln=en">Mefodev, Aleksandr</a> ; <a href="https://cds.cern.ch/search?f=author&p=Kholodenko%2C%20Sergey&ln=en">Kholodenko, Sergey</a> (INFN, Pisa) ; <a href="https://cds.cern.ch/search?f=author&p=Kurshetsov%2C%20Viktor&ln=en">Kurshetsov, Viktor</a> ; <a href="https://cds.cern.ch/search?f=author&p=Obraztsov%2C%20Vladimir&ln=en">Obraztsov, Vladimir</a> ; <a href="https://cds.cern.ch/search?f=author&p=Ostankov%2C%20Aleksandr&ln=en">Ostankov, Aleksandr</a> ; <a href="https://cds.cern.ch/search?f=author&p=Semenov%2C%20Vitali&ln=en">Semenov, Vitali</a> ; <a href="https://cds.cern.ch/search?f=author&p=Sugonyaev%2C%20Valentin&ln=en">Sugonyaev, Valentin</a> ; <a href="https://cds.cern.ch/search?f=author&p=Yushchenko%2C%20Oleg&ln=en">Yushchenko, Oleg</a> ; <a href="https://cds.cern.ch/search?f=author&p=Bician%2C%20Lubos&ln=en">Bician, Lubos</a> (Comenius U. ; Charles U.) ; <a href="https://cds.cern.ch/search?f=author&p=Blazek%2C%20Tomas&ln=en">Blazek, Tomas</a> (Comenius U.) ; <a href="https://cds.cern.ch/search?f=author&p=Cerny%2C%20Vladimir&ln=en">Cerny, Vladimir</a> (Comenius U.) ; <a href="https://cds.cern.ch/search?f=author&p=Koval%2C%20Michal&ln=en">Koval, Michal</a> (CERN ; 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Lett. B</i> 859 (2024) 139122</a> </a></td></tr> <tr><td class="formatRecordLabel"> DOI </td><td style="padding-left:5px;"><a href="http://dx.doi.org/10.1016/j.physletb.2024.139122" title="DOI" target="_blank">10.1016/j.physletb.2024.139122</a> <tr><td class="formatRecordLabel"> Subject category </td><td style="padding-left:5px;">Particle Physics - Experiment</td></tr> <tr><td class="formatRecordLabel"> Accelerator/Facility, Experiment </td><td style="padding-left:5px;"><a href="https://cds.cern.ch/search?p=CERN%20SPS&f=693__a">CERN SPS</a> ; <a href="https://cds.cern.ch/search?p=NA62&f=693__e">NA62</a></td></tr> <tr><td class="formatRecordLabel"> Keywords </td><td style="padding-left:5px;"><a href="https://cds.cern.ch/search?f=keyword&p=flavor%20physics&ln=en">flavor physics</a> ; <a href="https://cds.cern.ch/search?f=keyword&p=branching%20fraction&ln=en">branching fraction</a> ; <a href="https://cds.cern.ch/search?f=keyword&p=rare%20decay&ln=en">rare decay</a> ; <a href="https://cds.cern.ch/search?f=keyword&p=conservation%20law%20tests&ln=en">conservation law tests</a> ; <a href="https://cds.cern.ch/search?f=keyword&p=experimental%20results&ln=en">experimental results</a> ; <a href="https://cds.cern.ch/search?f=keyword&p=Kaon%20decays&ln=en">Kaon decays</a> ; <a href="https://cds.cern.ch/search?f=keyword&p=Lepton%20number%20conservation&ln=en">Lepton number conservation</a> ; <a href="https://cds.cern.ch/search?f=keyword&p=Lepton%20flavour%20conservation&ln=en">Lepton flavour conservation</a></td></tr> <tr><td class="formatRecordLabel"> Abstract </td><td style="padding-left:5px;">The first search for the lepton number violating decay $K^+ \to \pi^0 \pi^- \mu^+ e^+$ and lepton flavour violating decays $K^+ \to \pi^0 \pi^+ \mu^- e^+$, $K^+ \to \pi^0 \pi^+ \mu^+ e^-$ has been performed using a dataset collected by the NA62 experiment at CERN in 2016–2018. Upper limits of $2.9\times 10^{-10}$, $3.1 \times 10^{-10}$ and $5.0 \times 10^{-10}$, respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions.</td></tr> <tr><td class="formatRecordLabel"> Other source </td><td style="padding-left:5px;"><a href="http://inspirehep.net/record/2831122">Inspire</a></td></tr> <tr><td class="formatRecordLabel"> Copyright/License </td><td style="padding-left:5px;">Preprint: © 2024-2025 CERN (License: <a href="http://creativecommons.org/licenses/by/4.0/">CC-BY-4.0</a>)<br/>Publication: © 2024-2025 CERN (License: <a href="http://creativecommons.org/licenses/by/4.0/">CC BY 4.0</a>), sponsored by <a href="http://scoap3.org">SCOAP³</a></td></tr> <tr><td class="formatRecordLabel"> Submitted by </td><td style="padding-left:5px;"><a href="mailto:brigitte.bloch-devaux@cern.ch">brigitte.bloch-devaux@cern.ch</a></td></tr> </table> <br /><div style="max-width:1024px;margin:auto"><div style="overflow-x:auto;display:inline;width:100%;"><a href="/record/2899863/plots#0"><img style="vertical-align:middle;" src="https://cds.cern.ch/record/2899863/files/na62-sketch.png" title=" Schematic side view of the NA62 beamline and detector used in 2018." width="200px"/></a> <a href="/record/2899863/plots#1"><img style="vertical-align:middle;" src="https://cds.cern.ch/record/2899863/files/mpiee.png" title=" Reconstructed $m_{\pi ee}$ spectra for data (with statistical errors) and simulated samples obtained with the $K_{\pi ee}$ selection. The normalisation region is shown with vertical arrows. The data events are not weighted; see Section~\ref{sec:piee} for details." width="200px"/></a> <a href="/record/2899863/plots#2"><img style="vertical-align:middle;" src="https://cds.cern.ch/record/2899863/files/dp-pim.png" title=" Left: momentum difference ($\Delta p$) spectra for data and simulated samples obtained using a loose $K_{\pi\pi\mu e}$ selection without the $\Delta p$, $p_T$ and LAV veto conditions, and with the $m_{\pi\pi\mu e}$ condition inverted. Right: mass ($m_{\pi\pi\mu e}$) spectra for data and simulated samples for the full selection; the signal $m_{\pi\pi\mu e}$ regions, shown with arrows, are not masked. Top row: $K^+\to\pi^0\pi^-\mu^+e^+$ mode; middle row: $K^+\to\pi^0\pi^+\mu^-e^+$ mode; bottom row: $K^+\to\pi^0\pi^+\mu^+e^-$ mode." width="200px"/></a> <a href='/record/2899863/plots'>Show more plots</a></div></div><br /> <br/><div><div style="clear: both;"> </div></div> <script type="text/javascript"> // Initially hide: $(".longCaption").hide(); // Allow to toggle visibility: $(".toggleLongCaption").toggle(function(){ $(this).siblings(".longCaption").show('fast'); var thisElem = $(this); thisElem.text(thisElem.text() === "more" ? "less" : "more"); },function(){ $(this).siblings(".longCaption").hide('fast'); var thisElem = $(this); thisElem.text(thisElem.text() === "more" ? 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