PreprintCC BY 4.0arXiv
Search for the B0 → K0S τ+ τ- decay
Abstract
We present the first search for B0 → K0S τ+τ- decays. We look for signal decays in B0B̅0 events produced in asymmetric-energy electron-positron collisions. This work uses samples from the Belle and Belle~II detectors, comprising 1.16 billion Υ(4S) events. In Υ(4S)→ B0B̅0 decays, the non-signal B̅0 meson is fully reconstructed in a hadronic channel. For the signal B0 meson, τ-lepton decays into final states with a single charged particle are selected. We observe no evidence for the signal and set an upper limit on the branching fraction ℬ(B0→ K0S τ+τ-) < 8.3 × 10−4 at the 90\% confidence level. Combining this with the recent measurement of the isospin-partner decay B+→ K+τ+τ-, we determine an upper limit ℬ(B→ Kτ+τ-) < 5.4×10−4 at the 90\% confidence level.
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BibTeX
@misc{belle2026search,
title = {{Search for the $\boldsymbolB^0 \to K^0_\rm S τ^+ τ^-$ decay}},
author = {Belle and Belle II Collaborations and M. Abumusabh and I. Adachi and A. Aggarwal and Y. Ahn and H. Aihara and M. Akdag and N. Akopov and S. Alghamdi and M. Alhakami and A. Aloisio and N. Althubiti and K. Amos and M. Angelsmark and N. Anh Ky and C. Antonioli and D. M. Asner and H. Atmacan and T. Aushev and V. Aushev and R. Ayad and V. Babu and H. Bae and N. K. Baghel and S. Bahinipati and P. Bambade and Sw. Banerjee and M. Bartl and J. Baudot and A. Beaubien and F. Becherer and J. Becker and J. V. Bennett and V. Bertacchi and M. Bertemes and E. Bertholet and M. Bessner and S. Bettarini and V. Bhardwaj and B. Bhuyan and F. Bianchi and T. Bilka and D. Biswas and A. Bobrov and D. Bodrov and A. Bondar and G. Bonvicini and J. Borah and A. Boschetti and A. Bozek and M. Bračko and P. Branchini and R. A. Briere and T. E. Browder and A. Budano and S. Bussino and F. Callet and Q. Campagna and M. Campajola},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2607.25607},
eprint = {2607.25607},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.25607},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Search for the B^0 → K^0_S τ^+ τ^- decay
AU - Belle
AU - Belle II Collaborations
AU - M. Abumusabh
AU - I. Adachi
AU - A. Aggarwal
AU - Y. Ahn
AU - H. Aihara
AU - M. Akdag
AU - N. Akopov
AU - S. Alghamdi
AU - M. Alhakami
AU - A. Aloisio
AU - N. Althubiti
AU - K. Amos
AU - M. Angelsmark
AU - N. Anh Ky
AU - C. Antonioli
AU - D. M. Asner
AU - H. Atmacan
AU - T. Aushev
AU - V. Aushev
AU - R. Ayad
AU - V. Babu
AU - H. Bae
AU - N. K. Baghel
AU - S. Bahinipati
AU - P. Bambade
AU - Sw. Banerjee
AU - M. Bartl
AU - J. Baudot
AU - A. Beaubien
AU - F. Becherer
AU - J. Becker
AU - J. V. Bennett
AU - V. Bertacchi
AU - M. Bertemes
AU - E. Bertholet
AU - M. Bessner
AU - S. Bettarini
AU - V. Bhardwaj
AU - B. Bhuyan
AU - F. Bianchi
AU - T. Bilka
AU - D. Biswas
AU - A. Bobrov
AU - D. Bodrov
AU - A. Bondar
AU - G. Bonvicini
AU - J. Borah
AU - A. Boschetti
AU - A. Bozek
AU - M. Bračko
AU - P. Branchini
AU - R. A. Briere
AU - T. E. Browder
AU - A. Budano
AU - S. Bussino
AU - F. Callet
AU - Q. Campagna
AU - M. Campajola
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2607.25607
UR - https://arxiv.org/abs/2607.25607
AB - We present the first search for B^0 → K^0_S τ^+τ^- decays. We look for signal decays in B^0B̅^0 events produced in asymmetric-energy electron-positron collisions. This work uses samples from the Belle and Belle~II detectors, comprising 1.16 billion Υ(4S) events. In Υ(4S)→ B^0B̅^0 decays, the non-signal B̅^0 meson is fully reconstructed in a hadronic channel. For the signal B^0 meson, τ-lepton decays into final states with a single charged particle are selected. We observe no evidence for the signal and set an upper limit on the branching fraction ℬ(B^0→ K^0_S τ^+τ^-) < 8.3 × 10^−4 at the 90\% confidence level. Combining this with the recent measurement of the isospin-partner decay B^+→ K^+τ^+τ^-, we determine an upper limit ℬ(B→ Kτ^+τ^-) < 5.4×10^−4 at the 90\% confidence level.
ER -