Search for the charged lepton flavor violating decay $\psi(3686)\to e^{\pm}\mu^{\mp}$

BESIII Collaboration; M. Ablikim; M. N. Achasov; P. Adlarson; X. C. Ai; R. Aliberti; A. Amoroso; Q. An; Y. Bai; O. Bakina; Y. Ban; H. -R. Bao; V. Batozskaya; K. Begzsuren; N. Berger; M. Berlowski; M. Bertani; D. Bettoni; F. Bianchi; E. Bianco; A. Bortone; I. Boyko; R. A. Briere; A. Brueggemann; H. Cai; M. H. Cai; X. Cai; A. Calcaterra; G. F. Cao; N. Cao; S. A. Cetin; X. Y. Chai; J. F. Chang; G. R. Che; Y. Z. Che; C. H. Chen; Chao Chen; G. Chen; H. S. Chen; H. Y. Chen; M. L. Chen; S. J. Chen; S. L. Chen; S. M. Chen; T. Chen; X. R. Chen; X. T. Chen; X. Y. Chen; Y. B. Chen; Y. Q. Chen; Z. Chen; Z. J. Chen; Z. K. Chen; S. K. Choi; X. Chu; G. Cibinetto; F. Cossio; J. Cottee-Meldrum; J. J. Cui; H. L. Dai; J. P. Dai; A. Dbeyssi; R. E. de Boer; D. Dedovich; C. Q. Deng; Z. Y. Deng; A. Denig; I. Denysenko; M. Destefanis; F. De Mori; B. Ding; X. X. Ding; Y. Ding; Y. X. Ding; J. Dong; L. Y. Dong; M. Y. Dong; X. Dong; M. C. Du; S. X. Du; Y. Y. Duan; P. Egorov; G. F. Fan; J. J. Fan; Y. H. Fan; J. Fang; S. S. Fang; W. X. Fang; Y. Q. Fang; R. Farinelli; L. Fava; F. Feldbauer; G. Felici; C. Q. Feng; J. H. Feng; L. Feng; Q. X. Feng; Y. T. Feng; M. Fritsch; C. D. Fu

doi:10.1007/s11433-025-2901-7

arXiv · 2507.10331

Search for the charged lepton flavor violating decay $\psi(3686)\to e^{\pm}\mu^{\mp}$

BESIII Collaboration·M. Ablikim·M. N. Achasov·P. Adlarson·X. C. Ai·R. Aliberti·A. Amoroso·Q. An·Y. Bai·O. Bakina·Y. Ban·H. -R. Bao·V. Batozskaya·K. Begzsuren·N. Berger·M. Berlowski·M. Bertani·D. Bettoni·F. Bianchi·E. Bianco·A. Bortone·I. Boyko·R. A. Briere·A. Brueggemann·H. Cai·M. H. Cai·X. Cai·A. Calcaterra·G. F. Cao·N. Cao·S. A. Cetin·X. Y. Chai·J. F. Chang·G. R. Che·Y. Z. Che·C. H. Chen·Chao Chen·G. Chen·H. S. Chen·H. Y. Chen·M. L. Chen·S. J. Chen·S. L. Chen·S. M. Chen·T. Chen·X. R. Chen·X. T. Chen·X. Y. Chen·Y. B. Chen·Y. Q. Chen·Z. Chen·Z. J. Chen·Z. K. Chen·S. K. Choi·X. Chu·G. Cibinetto·F. Cossio·J. Cottee-Meldrum·J. J. Cui·H. L. Dai·J. P. Dai·A. Dbeyssi·R. E. de Boer·D. Dedovich·C. Q. Deng·Z. Y. Deng·A. Denig·I. Denysenko·M. Destefanis·F. De Mori·B. Ding·X. X. Ding·Y. Ding·Y. X. Ding·J. Dong·L. Y. Dong·M. Y. Dong·X. Dong·M. C. Du·S. X. Du·Y. Y. Duan·P. Egorov·G. F. Fan·J. J. Fan·Y. H. Fan·J. Fang·S. S. Fang·W. X. Fang·Y. Q. Fang·R. Farinelli·L. Fava·F. Feldbauer·G. Felici·C. Q. Feng·J. H. Feng·L. Feng·Q. X. Feng·Y. T. Feng·M. Fritsch·C. D. Fu

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Abstract

By analyzing $(2367.0\pm11.1)\times10^6$ $\psi(3686)$ events collected in $e^+e^-$ collisions at $\sqrt{s}=3.686~\rm GeV$ with the BESIII detector at the BEPCII collider, we report the first search for the charged lepton flavor violating decay $\psi(3686)\to e^{\pm}\mu^{\mp}$. No signal is found. An upper limit on the branching fraction $\mathcal{B}(\psi(3686)\to e^{\pm}\mu^{\mp})$ is determined to be $1.4\times10^{-8}$ at the 90\% confidence level.

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BESIII Collaboration, M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H. -R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, M. H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, G. R. Che, Y. Z. Che, C. H. Chen, Chao Chen, G. Chen, H. S. Chen, H. Y. Chen, M. L. Chen, S. J. Chen, S. L. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, X. Y. Chen, Y. B. Chen, Y. Q. Chen, Z. Chen, Z. J. Chen, Z. K. Chen, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. Cottee-Meldrum, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, C. Q. Deng, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. X. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, M. C. Du, S. X. Du, Y. Y. Duan, P. Egorov, G. F. Fan, J. J. Fan, Y. H. Fan, J. Fang, S. S. Fang, W. X. Fang, Y. Q. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, L. Feng, Q. X. Feng, Y. T. Feng, M. Fritsch, C. D. Fu. 2025-07-14. Search for the charged lepton flavor violating decay $\psi(3686)\to e^{\pm}\mu^{\mp}$. https://doi.org/10.1007/s11433-025-2901-7

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