Measurement of the CP Violation Parameters in B0 -> pi+ pi- Decays
hep-ex
/ Authors
Belle Collaboration, J. Dalseno, K. Prothmann, C. Kiesling, I. Adachi, H. Aihara, K. Arinstein, D. M. Asner, V. Aulchenko, T. Aushev
and 181 more authors
A. M. Bakich, A. Bala, A. Bay, P. Behera, V. Bhardwaj, B. Bhuyan, A. Bondar, G. Bonvicini, A. Bozek, M. Bračko, T. E. Browder, V. Chekelian, A. Chen, P. Chen, B. G. Cheon, K. Chilikin, R. Chistov, K. Cho, V. Chobanova, S. -K. Choi, Y. Choi, D. Cinabro, M. Danilov, Z. Doležal
/ Abstract
We present a measurement of the time-dependent charge-parity (CP) violation parameters in B0 -> pi+ pi- decays. The results are obtained from the final data sample containing 772 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain the CP violation parameters Acp = +0.33 +/- 0.06 (stat) +/- 0.03 (syst) and Scp = -0.64 +/- 0.08 (stat) +/- 0.03 (syst), where Acp and Scp represent the direct and mixing-induced CP asymmetry, respectively. Using an isospin analysis including results from other Belle measurements, we find 23.8 < phi2 < 66.8 degrees is disfavored at the 1 sigma level, where phi2 is one of the three interior angles of the CKM unitarity triangle related to B_{u,d} decays.