Improved Measurements of $CP$-Violating Asymmetry Amplitudes in $B^0 \to $\pi^+\pi^-$ Decays

• Published in: Physical review letters Vol. 95
• Main Authors: Aubert, B., Barate, R., Boutigny, D., Couderc, F., Karyotakis, Y., Lees, J.P., Poireau, V., Tisserand, V., Zghiche, A., Grauges-Pous, E., Palano, A., Pompili, A., Chen, J.C., Qi, N.D., Rong, G., Wang, P., Zhu, Y.S., Eigen, G., Ofte, I., Stugu, B., Abrams, G.S., Borgland, A.W., Breon, A.B., Brown, D.N., Button-Shafer, J., Cahn, R.N., Charles, E., Day, C.T., Gill, M.S., Gritsan, A.V., Groysman, Y., Jacobsen, R.G., Kadel, R.W., Kadyk, J., Kerth, L.T., Kolomensky, Yu. G., Kukartsev, G., Lynch, G., Mir, L.M., Oddone, P.J., Orimoto, T.J., Pripstein, M., Roe, N.A., Ronan, M.T., Wenzel, W.A., Barrett, M., Ford, K.E., Harrison, T.J., Hart, A.J., Hawkes, C.M., Morgan, S.E., Watson, A.T., Fritsch, M., Goetzen, K., Held, T., Koch, H., Lewandowski, B., Pelizaeus, M., Peters, K., Schroeder, T., Steinke, M., Boyd, J.T., Burke, J.P., Chevalier, N., Cottingham, W.N., Kelly, M.P., Latham, T.E., Wilson, F.F., Cuhadar-Donszelmann, T., Hearty, C., Knecht, N.S., Mattison, T.S., Mckenna, J.A., Thiessen, D., Khan, A., Kyberd, P., Teodorescu, L., Blinov, A.E., Blinov, V.E., Druzhinin, V.P., Golubev, V.B., Ivanchenko, V.N., Kravchenko, E.A., Onuchin, A.P., Serednyakov, S.I., Skovpen, Yu. I., Solodov, E.P., Yushkov, A.N., Best, D., Bruinsma, M., Chao, M., Eschrich, I., Kirkby, D., Lankford, A.J., Mandelkern, M., Mommsen, R.K., Roethel, W., Stoker, D.P., Buchanan, C., Hartfiel, B.L.
• Format: Journal Article
• Language: English
• Published: American Physical Society 07-10-2005
• Subjects: High Energy Physics - Experiment; Physics; CP invariance; B mesons; meson hadronic decay
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.95.151803

We present updated measurements of the CP-violating parameters S_pipi and C_pipi in B0 -> pi+pi- decays. Using a sample of 227 million Y(4S) -> BBbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we observe 467 +- 33 signal decays and measure S_pipi = -0.30 +- 0.17 (stat) +- 0.03 (syst), and C_pipi = -0.09 +- 0.15 (stat) +- 0.04 (syst).