We have searched for lepton-flavor-violating τ decays with a pseudoscalar meson (η, η′ and π0) using a data sample of 401 fb-1 collected with the Belle detector at the KEKB asymmetric-energy e+ e- collider. No evidence for these decays is found and we set the following upper limits on the branching fractions: B (τ- → e- η) < 9.2 × 10-8, B (τ- → μ- η) < 6.5 × 10-8, B (τ- → e- η′) < 1.6 × 10-7, B (τ- → μ- η′) < 1.3 × 10-7, B (τ- → e- π0) < 8.0 × 10-8 and B (τ- → μ- π0) < 1.2 × 10-7 at the 90% confidence level. These results improve our previously published upper limits by factors from 2.3 to 6.3.
|Number of pages||10|
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 2007 May 17|
Bibliographical noteFunding Information:
We are grateful to A. Brignole and A. Rossi for enlightening discussions. We thank the KEKB group for the excellent operation of the accelerator, the KEK cryogenics group for the efficient operation of the solenoid, and the KEK computer group and the National Institute of Informatics for valuable computing and Super-SINET network support. We acknowledge support from the Ministry of Education, Culture, Sports, Science, and Technology of Japan and the Japan Society for the Promotion of Science; the Australian Research Council and the Australian Department of Education, Science and Training; the National Science Foundation of China and the Knowledge Innovation Program of the Chinese Academy of Sciences under contract No. 10575109 and IHEP-U-503; the Department of Science and Technology of India; the BK21 program of the Ministry of Education of Korea, the CHEP SRC program and Basic Research program (grant No. R01-2005-000-10089-0) of the Korea Science and Engineering Foundation, and the Pure Basic Research Group program of the Korea Research Foundation; the Polish State Committee for Scientific Research; the Ministry of Education and Science of the Russian Federation and the Russian Federal Agency for Atomic Energy; the Slovenian Research Agency; the Swiss National Science Foundation; the National Science Council and the Ministry of Education of Taiwan; and the US Department of Energy.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics