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arXiv · 2005.01230

Precision measurement of the ${\cal B}(\Upsilon(3S)\to\tau^+\tau^-)/{\cal B}(\Upsilon(3S)\to\mu^+\mu^-)$ ratio

J. P. Lees·V. Poireau·V. Tisserand·E. Grauges·A. Palano·G. Eigen·D. N. Brown·Yu. G. Kolomensky·M. Fritsch·H. Koch·T. Schroeder·R. Cheaib·C. Hearty·T. S. Mattison·J. A. McKenna·R. Y. So·V. E. Blinov·A. R. Buzykaev·V. P. Druzhinin·V. B. Golubev·E. A. Kozyrev·E. A. Kravchenko·A. P. Onuchin·S. I. Serednyakov·Yu. I. Skovpen·E. P. Solodov·K. Yu. Todyshev·A. J. Lankford·B. Dey·J. W. Gary·O. Long·A. M. Eisner·W. S. Lockman·W. Panduro Vazquez·D. S. Chao·C. H. Cheng·B. Echenard·K. T. Flood·D. G. Hitlin·J. Kim·Y. Li·D. X. Lin·T. S. Miyashita·P. Ongmongkolkul·J. Oyang·F. C. Porter·M. Röhrken·Z. Huard·B. T. Meadows·B. G. Pushpawela·M. D. Sokoloff·L. Sun·J. G. Smith·S. R. Wagner·D. Bernard·M. Verderi·D. Bettoni·C. Bozzi·R. Calabrese·G. Cibinetto·E. Fioravanti·I. Garzia·E. Luppi·V. Santoro·A. Calcaterra·R. de Sangro·G. Finocchiaro·S. Martellotti·P. Patteri·I. M. Peruzzi·M. Piccolo·M. Rotondo·A. Zallo·S. Passaggio·C. Patrignani·B. J. Shuve·H. M. Lacker·B. Bhuyan·U. Mallik·C. Chen·J. Cochran·S. Prell·A. V. Gritsan·N. Arnaud·M. Davier·F. Le Diberder·A. M. Lutz·G. Wormser·D. J. Lange·D. M. Wright·J. P. Coleman·E. Gabathuler·D. E. Hutchcroft·D. J. Payne·C. Touramanis·A. J. Bevan·F. Di Lodovico·R. Sacco·G. Cowan·Sw. Banerjee
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Abstract

We report on a precision measurement of the ratio ${\cal R}_{\tau\mu}^{\Upsilon(3S)} = {\cal B}(\Upsilon(3S)\to\tau^+\tau^-)/{\cal B}(\Upsilon(3S)\to\mu^+\mu^-)$ using data collected with the BaBar detector at the SLAC PEP-II $e^+e^-$ collider. The measurement is based on a 28 fb$^{-1}$ data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million $\Upsilon(3S)$ mesons. The ratio is measured to be ${\cal R}_{\tau\mu}^{\Upsilon(3S)} = 0.966 \pm 0.008_\mathrm{stat} \pm 0.014_\mathrm{syst}$ and is in agreement with the Standard Model prediction of 0.9948 within 2 standard deviations. The uncertainty in ${\cal R}_{\tau\mu}^{\Upsilon(3S)}$ is almost an order of magnitude smaller than the only previous measurement.

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J. P. Lees, V. Poireau, V. Tisserand, E. Grauges, A. Palano, G. Eigen, D. N. Brown, Yu. G. Kolomensky, M. Fritsch, H. Koch, T. Schroeder, R. Cheaib, C. Hearty, T. S. Mattison, J. A. McKenna, R. Y. So, V. E. Blinov, A. R. Buzykaev, V. P. Druzhinin, V. B. Golubev, E. A. Kozyrev, E. A. Kravchenko, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, E. P. Solodov, K. Yu. Todyshev, A. J. Lankford, B. Dey, J. W. Gary, O. Long, A. M. Eisner, W. S. Lockman, W. Panduro Vazquez, D. S. Chao, C. H. Cheng, B. Echenard, K. T. Flood, D. G. Hitlin, J. Kim, Y. Li, D. X. Lin, T. S. Miyashita, P. Ongmongkolkul, J. Oyang, F. C. Porter, M. Röhrken, Z. Huard, B. T. Meadows, B. G. Pushpawela, M. D. Sokoloff, L. Sun, J. G. Smith, S. R. Wagner, D. Bernard, M. Verderi, D. Bettoni, C. Bozzi, R. Calabrese, G. Cibinetto, E. Fioravanti, I. Garzia, E. Luppi, V. Santoro, A. Calcaterra, R. de Sangro, G. Finocchiaro, S. Martellotti, P. Patteri, I. M. Peruzzi, M. Piccolo, M. Rotondo, A. Zallo, S. Passaggio, C. Patrignani, B. J. Shuve, H. M. Lacker, B. Bhuyan, U. Mallik, C. Chen, J. Cochran, S. Prell, A. V. Gritsan, N. Arnaud, M. Davier, F. Le Diberder, A. M. Lutz, G. Wormser, D. J. Lange, D. M. Wright, J. P. Coleman, E. Gabathuler, D. E. Hutchcroft, D. J. Payne, C. Touramanis, A. J. Bevan, F. Di Lodovico, R. Sacco, G. Cowan, Sw. Banerjee. 2020-05-04. Precision measurement of the ${\cal B}(\Upsilon(3S)\to\tau^+\tau^-)/{\cal B}(\Upsilon(3S)\to\mu^+\mu^-)$ ratio. https://doi.org/10.1103/physrevlett.125.241801

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