Search for lepton flavor-violating decay modes $B^0 \to K^{*0}\tau^{\pm}\ell^{\mp}(\ell = e,\mu)$ with hadronic B-tagging at Belle and Belle II

Adachi, Ichiro (author), Borah, Jyotirmoi (author), Bračko, Marko (author), Korpar, Samo (author), Križan, Peter (author), Pestotnik, Rok (author), Podobnik, Tomaž (author), Šantelj, Luka (author), Starič, Marko (author)

We present the results of a search for the charged-lepton-flavor violating decays $B^0\rightarrow K^{*0}\tau^\pm\ell^\mp$, where $\ell^\mp$ is either an electron or a muon. The results are based on 365 fb$^{-1}$ and 711 fb$^{-1}$ datasets collected with the Belle II and Belle detectors, respectively. We use an exclusive hadronic $B$-tagging technique, and search for a signal decay in the system recoiling against a fully reconstructed $B$ meson. We find no evidence for $B^0\rightarrow K^{*0}\tau^\pm\ell^\mp$ decays and set upper limits on the branching fractions in the range of (2.9–6.4)$\times10^{-5}$ at 90% confidence level.

• Language: English
• Keywords: experimental physics, physics of elementary particles, flavour physics, particle decays
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 21 str.
• Numbering: Vol. 2025, art. no. 184
• PID: 20.500.12556/RUL-178840
• UDC: 539.1
• ISSN on article: 1029-8479
• DOI: 10.1007/JHEP08(2025)184
• COBISS.SI-ID: 266677507
• Publication date in RUL: 30.01.2026

Record is a part of a journal

• Title: The journal of high energy physics
• Shortened title: J. high energy phys.
• Publisher: SISSA
• ISSN: 1029-8479
• COBISS.SI-ID: 1314148

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: eksperimentalna fizika, fizika osnovnih delcev, fizika okusov, razpadi delcev

Projects

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: J1-9124
• Name: Napredne metode za identifikacijo hadronov pri eksperimentu Belle II

• Funder: ARIS - Slovenian Research and Innovation Agency
• Project number: P1-0135
• Name: Eksperimentalna fizika osnovnih delcev