An improved search for the electric dipole moment of the τ 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. K. Behera, M. Bessner, B. Bhuyan, T. Bilka, J. P. Biswal, A. Bobrov, G. Bonvicini, A. Bożek, 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. B. 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, M. Iwasaki, W. W. Jacobs, E.-J. Jang, Y. Jin, C. Joo, K. K. Joo, Yuji Katō, T. Kawasaki, H. Kichimi, C. Kiesling, C. H. Kim, D. Y. Kim, S. H. Kim, Y.-K. Kim, T. D. Kimmel, K. Kinoshita, P. Kodyš, T. Konno, S. Korpar, P. Križan, R. Kroeger, P. Krokovny, R. Kulasiri, M. Kumar, Ramanuj 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
Abstract
A bstract We report a measurement of the electric dipole moment of the τ lepton ( dτ ) using an 833 fb − 1 data sample collected near the Υ(4 S ) 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 τ as Re( d τ ) = ( − 0 . 62 ± 0 . 63) × 10 − 17 e cm and Im( d τ ) = ( − 0 . 40 ± 0 . 32) × 10 − 17 e 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.