Search for b → u Transitions in B − → D0 (–) K − and B − → D∗0 (–) K − The BABAR Collaboration

We report on searches for B → D0 (–) K and B → D∗0 (–) K, with D∗0 (–) → D0 (–) π0 or D∗0 (–) → D0 (–) γ, and D0 (–) → K+π− (and charge conjugates). These final states, which we denote as [Kπ]DK and [Kπ]D∗K , can be reached through the b → c transition B → D(∗)0K− followed by the doubly Cabibbo-suppressed D0 → K+π−, or through the b → u transition B → D(∗)0K− followed by the Cabibbo-favored D0 → K+π−, or through interference of the two. Our results are based on 227 million Υ (4S) → BB decays collected with the BABAR detector at SLAC. We set preliminary limits on the ratios RKπ ≡ Γ(B+ → [Kπ]DK) + Γ(B → [Kπ]DK) Γ(B+ → [Kπ]DK) + Γ(B− → [Kπ]DK) < 0.030 (90% C.L.) and RKπ ≡ Γ(B+ → [Kπ]D∗K) + Γ(B → [Kπ]D∗K) Γ(B+ → [Kπ]D∗K) + Γ(B− → [Kπ]D∗K) < 0.021 (90% C.L.), where the central values are RKπ = 0.013±0.011 0.009 and RKπ = 0.003±0.010 0.007. These limits constrain the amplitude ratios rB ≡ |A(B− → D0K−)/A(B− → D0K−)| < 0.23 and r B ≡ |A(B− → D∗0K−)/A(B− → D∗0K−)| < 0.21 at the 90% confidence level. Submitted to the 32nd International Conference on High-Energy Physics, ICHEP 04, 16 August—22 August 2004, Beijing, China Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309 Work supported in part by Department of Energy contract DE-AC03-76SF00515. hep-ex/0408028 The BABAR Collaboration, B. Aubert, R. Barate, D. Boutigny, F. Couderc, J.-M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, V. Tisserand, A. Zghiche Laboratoire de Physique des Particules, F-74941 Annecy-le-Vieux, France A. Palano, A. Pompili Università di Bari, Dipartimento di Fisica and INFN, I-70126 Bari, Italy J. C. Chen, N. D. Qi, G. Rong, P. Wang, Y. S. Zhu Institute of High Energy Physics, Beijing 100039, China G. Eigen, I. Ofte, B. Stugu University of Bergen, Inst. of Physics, N-5007 Bergen, Norway G. S. Abrams, A. W. Borgland, A. B. Breon, D. N. Brown, J. Button-Shafer, R. N. Cahn, E. Charles, C. T. Day, M. S. Gill, A. V. Gritsan, Y. Groysman, R. G. Jacobsen, R. W. Kadel, J. Kadyk, L. T. Kerth, Yu. G. Kolomensky, G. Kukartsev, G. Lynch, L. M. Mir, P. J. Oddone, T. J. Orimoto, M. Pripstein, N. A. Roe, M. T. Ronan, V. G. Shelkov, W. A. Wenzel Lawrence Berkeley National Laboratory and University of California, Berkeley, CA 94720, USA M. Barrett, K. E. Ford, T. J. Harrison, A. J. Hart, C. M. Hawkes, S. E. Morgan, A. T. Watson University of Birmingham, Birmingham, B15 2TT, United Kingdom M. Fritsch, K. Goetzen, T. Held, H. Koch, B. Lewandowski, M. Pelizaeus, M. Steinke Ruhr Universität Bochum, Institut für Experimentalphysik 1, D-44780 Bochum, Germany J. T. Boyd, N. Chevalier, W. N. Cottingham, M. P. Kelly, T. E. Latham, F. F. Wilson University of Bristol, Bristol BS8 1TL, United Kingdom T. Cuhadar-Donszelmann, C. Hearty, N. S. Knecht, T. S. Mattison, J. A. McKenna, D. Thiessen University of British Columbia, Vancouver, BC, Canada V6T 1Z1 A. Khan, P. Kyberd, L. Teodorescu Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom A. E. Blinov, V. E. Blinov, V. P. Druzhinin, V. B. Golubev, V. N. Ivanchenko, E. A. Kravchenko, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, E. P. Solodov, A. N. Yushkov Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia D. Best, M. Bruinsma, M. Chao, I. Eschrich, D. Kirkby, A. J. Lankford, M. Mandelkern, R. K. Mommsen, W. Roethel, D. P. Stoker University of California at Irvine, Irvine, CA 92697, USA C. Buchanan, B. L. Hartfiel University of California at Los Angeles, Los Angeles, CA 90024, USA S. D. Foulkes, J. W. Gary, B. C. Shen, K. Wang University of California at Riverside, Riverside, CA 92521, USA