Peer-reviewedCC BYPhys.Rev.Lett.
Search for the Decay B+→K+τ+τ- Using Data from the Belle and Belle II Experiments
Abstract
We report a search for the rare decay B^{+}→K^{+}τ^{+}τ^{-} using 1.2×10^{9} ϒ(4S) mesons produced near threshold in electron-positron collisions and collected by the Belle and Belle II experiments. We fully reconstruct the hadronic decay of one B meson produced in the ϒ(4S)→B^{+}B^{-} decay, and search for B^{±}→K^{±}τ^{+}τ^{-} candidates among the remaining collision products, reconstructing a charged kaon and leptonic decays of the τ leptons. We optimize the selection for best sensitivity and look for an excess over background at low values of the residual energy detected in the calorimeter after full event reconstruction. We observe no significant excess and set the limit B(B^{+}→K^{+}τ^{+}τ^{-})<0.56×10^{-3} at the 90% confidence level, improving on the only previous result by a factor of four.
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BibTeX
@article{abumusabh2026search,
title = {{Search for the Decay B+→K+τ+τ- Using Data from the Belle and Belle II Experiments}},
author = {Merna Abumusabh and Ichiro Adachi and Karol Mateusz Adamczyk and Agrim Aggarwal and Latika Aggarwal and Hossain Ahmed and Yongheon Ahn and Hiroaki Aihara and Norayr Akopov and Saleh Alghamdi and Mohammad Hasan Alhakami and Alberto Aloisio and Numa Althubiti and Kieran Amos and Martin Angelsmark and Anh-Ky Nguyen and Cecilia Antonioli and David Mark Asner and Hulya Atmacan and Tagir Aushev and Rachid Ayad and Varghese Babu and Hanwook Bae and Naveen Kumar Baghel and Seema Bahinipati and Philip Bambade and Swagato Banerjee and Matthew Barrett and Martin Bartl and Jerome Baudot and Anselm Baur and Alexandre Beaubien and Fabian Horst Becherer and Juergen Becker and Jake Bennett and Florian Bernlochner and Valerio Bertacchi and Michel Bertemes and Emilie Bertholet and Martin Bessner and Stefano Bettarini and Vishal Bhardwaj and Fabrizio Bianchi and Tadeas Bilka and Diptaparna Biswas and Alexander Bobrov and Denis Bodrov and Alexander E Bondar and Giovanni Bonvicini and Jyotirmoi Borah and Alessandro Boschetti and Andrzej Bozek and Marko Bracko and Paolo Branchini and Roy Briere and Thomas Earl Browder and Antonio Budano and Severino Bussino and Quinn Campagna and Marcello Campajola},
journal = {Phys.Rev.Lett.},
year = {2026},
month = sep,
doi = {10.1103/12f4-z51q},
eprint = {2603.24437},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05735460v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Search for the Decay B+→K+τ+τ- Using Data from the Belle and Belle II Experiments
AU - Merna Abumusabh
AU - Ichiro Adachi
AU - Karol Mateusz Adamczyk
AU - Agrim Aggarwal
AU - Latika Aggarwal
AU - Hossain Ahmed
AU - Yongheon Ahn
AU - Hiroaki Aihara
AU - Norayr Akopov
AU - Saleh Alghamdi
AU - Mohammad Hasan Alhakami
AU - Alberto Aloisio
AU - Numa Althubiti
AU - Kieran Amos
AU - Martin Angelsmark
AU - Anh-Ky Nguyen
AU - Cecilia Antonioli
AU - David Mark Asner
AU - Hulya Atmacan
AU - Tagir Aushev
AU - Rachid Ayad
AU - Varghese Babu
AU - Hanwook Bae
AU - Naveen Kumar Baghel
AU - Seema Bahinipati
AU - Philip Bambade
AU - Swagato Banerjee
AU - Matthew Barrett
AU - Martin Bartl
AU - Jerome Baudot
AU - Anselm Baur
AU - Alexandre Beaubien
AU - Fabian Horst Becherer
AU - Juergen Becker
AU - Jake Bennett
AU - Florian Bernlochner
AU - Valerio Bertacchi
AU - Michel Bertemes
AU - Emilie Bertholet
AU - Martin Bessner
AU - Stefano Bettarini
AU - Vishal Bhardwaj
AU - Fabrizio Bianchi
AU - Tadeas Bilka
AU - Diptaparna Biswas
AU - Alexander Bobrov
AU - Denis Bodrov
AU - Alexander E Bondar
AU - Giovanni Bonvicini
AU - Jyotirmoi Borah
AU - Alessandro Boschetti
AU - Andrzej Bozek
AU - Marko Bracko
AU - Paolo Branchini
AU - Roy Briere
AU - Thomas Earl Browder
AU - Antonio Budano
AU - Severino Bussino
AU - Quinn Campagna
AU - Marcello Campajola
PY - 2026
DA - 2026/09/02
JO - Phys.Rev.Lett.
DO - 10.1103/12f4-z51q
UR - https://hal.science/hal-05735460v1
AB - We report a search for the rare decay B^{+}→K^{+}τ^{+}τ^{-} using 1.2×10^{9} ϒ(4S) mesons produced near threshold in electron-positron collisions and collected by the Belle and Belle II experiments. We fully reconstruct the hadronic decay of one B meson produced in the ϒ(4S)→B^{+}B^{-} decay, and search for B^{±}→K^{±}τ^{+}τ^{-} candidates among the remaining collision products, reconstructing a charged kaon and leptonic decays of the τ leptons. We optimize the selection for best sensitivity and look for an excess over background at low values of the residual energy detected in the calorimeter after full event reconstruction. We observe no significant excess and set the limit B(B^{+}→K^{+}τ^{+}τ^{-})<0.56×10^{-3} at the 90% confidence level, improving on the only previous result by a factor of four.
ER -