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ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2007, vol. 98, p. -

Evidence for CP violation in B0→D+D- Decays

Fratina S., Abe K., Abe K., Adachi I., Aihara H., Anipko D., Arinstein K., Aushev T., Bakich A. M., Barberio E., Bay A., Belous K., Bitenc U., Bizjak I., Bondar A., Bozek A., Bračko M., Brodzicka J., Browder T. E., Chang M. C., Chang P., Chao Y., Chen A., Chen K. F., Chen W. T., Cheon B. G., Chistov R., Choi Y., Choi Y. K., Cole S., Dalseno J., Dash M., Drutskoy A., Eidelman S., Go A., Golob B., Gorišek A., Ha H., Haba J., Hara K., Hazumi M., Heffernan D., Hokuue T., Hoshi Y., Hou W. S., Iijima T., Inami K., Ishikawa A., Ishino H., Itoh R., Iwasaki M., Iwasaki Y., Kaji H., Kang J. H., Katayama N., Kawai H., Kawasaki T., Kichimi H., Kim H. J., Kim H. O., Kim S. K., Kim Y. J., Kinoshita K., Korpar S., Križan P., Krokovny P., Kulasiri R., Kumar R., Kuo C. C., Kuzmin A., Kwon Y. J., Lee M. J., Lee S. E., Lesiak T., Limosani A., Lin S. W., Liventsev D., Mandl F., Matsumoto T., Matyja A., McOnie S., Medvedeva T., Mitaroff W., Miyabayashi K., Miyake H., Miyata H., Miyazaki Y., Mizuk R., Moloney G. R., Mori T., Nakano E., Nakao M., Nakazawa H., Nishida S.

We report measurements of the branching fraction and CP violation parameters in B0→D+D- decays. The results are based on a data sample that contains 535×106 BB̄ pairs collected at the Υ(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97±0.20(stat)±0.20(syst)]×10-4 for the branching fraction of B0→D+D-. The measured values of the CP violation parameters are S=-1.13±0.37±0.09, A=0.91±0.23±0.06, where the first error is statistical and the second is systematic. We find evidence of CP violation in B0→D+D- at the 4.1σ confidence level. While the value of S is consistent with expectations from other measurements, the value of the parameter A favors large direct CP violation at the 3.2σ confidence level, in contradiction to standard model expectations. © 2007 The American Physical Society.