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arXiv · 2108.11543

An improved search for the electric dipole moment of the $\tau$ lepton

K. Inami·K. Hayasaka·I. Adachi·H. Aihara·S. Al Said·D. M. Asner·V. Aulchenko·T. Aushev·R. Ayad·V. Babu·S. Bahinipati·P. Behera·M. Bessner·B. Bhuyan·T. Bilka·J. Biswal·A. Bobrov·G. Bonvicini·A. Bozek·M. Bračko·T. E. Browder·M. Campajola·D. Červenkov·B. G. Cheon·K. Chilikin·H. E. Cho·K. Cho·Y. Choi·S. Choudhury·D. Cinabro·S. Cunliffe·S. Das·G. De Nardo·R. Dhamija·F. Di Capua·Z. Doležal·T. V. Dong·S. Dubey·S. Eidelman·D. Epifanov·T. Ferber·B. G. Fulsom·R. Garg·V. Gaur·N. Gabyshev·A. Garmash·A. Giri·P. Goldenzweig·B. Golob·D. Greenwald·K. Gudkova·C. Hadjivasiliou·O. Hartbrich·H. Hayashii·M. T. Hedges·W. -S. Hou·C. -L. Hsu·T. Iijima·G. Inguglia·A. Ishikawa·R. Itoh·M. Iwasaki·Y. Iwasaki·W. W. Jacobs·E. -J. Jang·Y. Jin·C. W. Joo·K. K. Joo·Y. Kato·T. Kawasaki·H. Kichimi·C. H. Kim·D. Y. Kim·S. H. Kim·Y. -K. Kim·T. D. Kimmel·K. Kinoshita·P. Kodyš·T. Konno·S. Korpar·R. Kroeger·P. Krokovny·R. Kulasiri·M. Kumar·R. Kumar·K. Kumara·Y. -J. Kwon·K. Lalwani·J. S. Lange·S. C. Lee·C. H. Li·J. Li·L. K. Li·Y. B. Li·L. Li Gioi·J. Libby·D. Liventsev·C. MacQueen·M. Masuda·T. Matsuda
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Abstract

We report a measurement of the electric dipole moment of the $\tau$ lepton ($d_\tau$) using an 833~fb$^{-1}$ data sample collected near the $\Upsilon(4S)$ resonance, with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. Using an optimal observable method, we obtain the real and imaginary parts of $d_\tau$ as ${\rm Re}(d_\tau) = ( -0.62 \pm 0.63 ) \times 10^{-17} ~e{\rm cm}$ and ${\rm Im}(d_\tau) = ( -0.40 \pm 0.32 ) \times 10^{-17} ~e{\rm cm}$, respectively. These results are consistent with null electric dipole moment at the present level of experimental sensitivity and improve the sensitivity by about a factor of three.

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K. Inami, K. Hayasaka, I. Adachi, H. Aihara, S. Al Said, D. M. Asner, V. Aulchenko, T. Aushev, R. Ayad, V. Babu, S. Bahinipati, P. Behera, M. Bessner, B. Bhuyan, T. Bilka, J. Biswal, A. Bobrov, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, M. Campajola, D. Červenkov, B. G. Cheon, K. Chilikin, H. E. Cho, K. Cho, Y. Choi, S. Choudhury, D. Cinabro, S. Cunliffe, S. Das, G. De Nardo, R. Dhamija, F. Di Capua, Z. Doležal, T. V. Dong, S. Dubey, S. Eidelman, D. Epifanov, T. Ferber, B. G. Fulsom, R. Garg, V. Gaur, N. Gabyshev, A. Garmash, A. Giri, P. Goldenzweig, B. Golob, D. Greenwald, K. Gudkova, C. Hadjivasiliou, O. Hartbrich, H. Hayashii, M. T. Hedges, W. -S. Hou, C. -L. Hsu, T. Iijima, G. Inguglia, A. Ishikawa, R. Itoh, M. Iwasaki, Y. Iwasaki, W. W. Jacobs, E. -J. Jang, Y. Jin, C. W. Joo, K. K. Joo, Y. Kato, T. Kawasaki, H. Kichimi, C. H. Kim, D. Y. Kim, S. H. Kim, Y. -K. Kim, T. D. Kimmel, K. Kinoshita, P. Kodyš, T. Konno, S. Korpar, R. Kroeger, P. Krokovny, R. Kulasiri, M. Kumar, R. Kumar, K. Kumara, Y. -J. Kwon, K. Lalwani, J. S. Lange, S. C. Lee, C. H. Li, J. Li, L. K. Li, Y. B. Li, L. Li Gioi, J. Libby, D. Liventsev, C. MacQueen, M. Masuda, T. Matsuda. 2021-08-26. An improved search for the electric dipole moment of the $\tau$ lepton. https://doi.org/10.1007/jhep04(2022)110

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