Evidence for B+ → K+ ν¯ν decays

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F24%3A10494120" target="_blank" >RIV/00216208:11320/24:10494120 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=rm2BRxeoQy" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=rm2BRxeoQy</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1103/PhysRevD.109.112006" target="_blank" >10.1103/PhysRevD.109.112006</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Evidence for B+ → K+ ν¯ν decays

Popis výsledku v původním jazyce

We search for the rare decay Bþ RIGHTWARDS ARROW Kþν-ν in a 362 fb-1 sample of electron-positron collisions at theϒð4SÞ resonance collected with the Belle II detector at the SuperKEKB collider. We use the inclusiveproperties of the accompanying B meson in ϒð4SÞ RIGHTWARDS ARROW BB- events to suppress background from other decaysof the signal B candidate and light-quark pair production. We validate the measurement with an auxiliaryanalysis based on a conventional hadronic reconstruction of the accompanying B meson. For backgroundsuppression, we exploit distinct signal features using machine learning methods tuned with simulated data.The signal-reconstruction efficiency and background suppression are validated through various controlchannels. The branching fraction is extracted in a maximum likelihood fit. Our inclusive and hadronicanalyses yield consistent results for the Bþ RIGHTWARDS ARROW Kþν-ν branching fraction of 1/22.7 0.5ðstatÞ 0.5ðsystÞ x10-5 and 1/21.1þ0.9-0.8ðstatÞþ0.8-0.5ðsystÞ x 10-5, respectively. Combining the results, we determine the branchingfraction of the decay Bþ RIGHTWARDS ARROW Kþν-ν to be 1/22.3 0.5ðstatÞþ0.5-0.4ðsystÞ x 10-5, providing the first evidence forthis decay at 3.5 standard deviations. The combined result is 2.7 standard deviations above the standardmodel expectation.

Název v anglickém jazyce

Evidence for B+ → K+ ν¯ν decays

Popis výsledku anglicky

We search for the rare decay Bþ RIGHTWARDS ARROW Kþν-ν in a 362 fb-1 sample of electron-positron collisions at theϒð4SÞ resonance collected with the Belle II detector at the SuperKEKB collider. We use the inclusiveproperties of the accompanying B meson in ϒð4SÞ RIGHTWARDS ARROW BB- events to suppress background from other decaysof the signal B candidate and light-quark pair production. We validate the measurement with an auxiliaryanalysis based on a conventional hadronic reconstruction of the accompanying B meson. For backgroundsuppression, we exploit distinct signal features using machine learning methods tuned with simulated data.The signal-reconstruction efficiency and background suppression are validated through various controlchannels. The branching fraction is extracted in a maximum likelihood fit. Our inclusive and hadronicanalyses yield consistent results for the Bþ RIGHTWARDS ARROW Kþν-ν branching fraction of 1/22.7 0.5ðstatÞ 0.5ðsystÞ x10-5 and 1/21.1þ0.9-0.8ðstatÞþ0.8-0.5ðsystÞ x 10-5, respectively. Combining the results, we determine the branchingfraction of the decay Bþ RIGHTWARDS ARROW Kþν-ν to be 1/22.3 0.5ðstatÞþ0.5-0.4ðsystÞ x 10-5, providing the first evidence forthis decay at 3.5 standard deviations. The combined result is 2.7 standard deviations above the standardmodel expectation.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10300 - Physical sciences

Projekt

<a href="/cs/project/GA22-18469S" target="_blank" >GA22-18469S: Studium jevů za Standardním modelem ve flavor sektoru na experimentu Belle II</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2024

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Physical Review D

ISSN

2470-0010

e-ISSN

2470-0029

Svazek periodika

109

Číslo periodika v rámci svazku

11

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

29

Strana od-do

112006

Kód UT WoS článku

001270351400001

EID výsledku v databázi Scopus

2-s2.0-85195461944