Search for the charged lepton flavor violating decay J/ψ → eτ

Authors：Ablikim, M.; Achasov, M. N.; Adlarson, P.; Ahmed, S.; Albrecht, M.; Aliberti, R.; Amoroso, A.; An, M. R.; An, Q.; Bai, X. H.; Bai, Y.; Bakina, O.; Ferroli, R. Baldini; Balossino, I; Ban, Y.; Begzsuren, K.; Berger, N.; Bertani, M.; Bettoni, D.; Bianchi, F.; Bloms, J.; Bortone, A.; Boyko, I; Briere, R. A.; Cai, H.; Cai, X.; Calcaterra, A.; Cao, G. F.; Cao, N.; Cetin, S. A.; Chang, J. F.; Chang, W. L.; Chelkov, G.; Chen, D. Y.; Chen, G.; Chen, H. S.; Chen, M. L.; Chen, S. J.; Chen, X. R.

Source：Physical Review D, 2021, 103(11): 112007.

DOI：10.1103/PhysRevD.103.112007

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A search for the charged lepton flavor violating decay J/psi -> e(+/-)tau(-/+) with tau(-/+) -> pi(-/+)pi(0)nu(tau) is performed with about 10 x 10(9) J/psi events collected with the BESIII detector at the BEPCII. No significant signal is observed, and an upper limit is set on the branching fraction B(J/psi -> e(+/-)tau(-/+)() <) 7.5 x 10(-8) at the 90% confidence level. This improves the previously published limit by two orders of magnitude.