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We report on the first search for electron-muon lepton flavor violation (LFV) in the decay of a b quark and b antiquark bound state. We look for the LFV decay ϒ(3S) → e ± μ in a sample of 118 million ϒ(3S) mesons from 27 fb−1 of data collected with the BABAR detector at the SLAC PEP-II e+e collider operating with a 10.36 GeV center-of-mass energy. No evidence for a signal is found, and we set a limit on the branching fraction B[ϒ(3S) → e ± μ]< 3.6 × 10−7 at 90% C. L. This result can be interpreted as a limit ΛNP=g2NP > 80 TeV on the energy scale ΛNP divided by the coupling-squared g2NP of relevant new physics (NP).

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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

APA Citation

Lees, J. P., Poireau, V., Tisserand, V., Grauges, E., Palano, A., Eigen, G., Brown, D. N., Kolomensky, Yu. G., Fritsch, M., Koch, H., Schroeder, T., Cheaib, R., Hearty, C., Mattison, T. S., McKenna, J. A., So, R. Y., Blinov, V. E., Buzykaev, A. R., Druzhinin, V. P., … Wu, S. L. (2022b). Search for lepton flavor violation in . Physical Review Letters, 128(9).

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