Search for B 0 → a + 0 (980)π− The BABAR Collaboration

We present preliminary results of a search for the decay B0 → a0 (980)π − among 22.7 million Υ (4S) → BB pairs collected by the BABAR detector at PEP-II. Using improved background suppression techniques and optimal signal extraction for rare decay searches, an excess of events over expected background is observed at the level of 3.7 standard deviations. This corresponds to the branching fraction B(B0 → a0 (a + 0 → ηπ +)π−) = (6.2 −2.5 ± 1.1) × 10 −6, where the first error is statistical and the second is systematic. The 90% confidence level upper limit is 11.5 × 10−6. Submitted to the 20 International Symposium on Lepton and Photon Interactions at High Energies 7/23/2001—7/28/2001, Rome, Italy Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309 Work supported in part by Department of Energy contract DE-AC03-76SF00515. The BABAR Collaboration, B. Aubert, D. Boutigny, J.-M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, P. Robbe, V. Tisserand Laboratoire de Physique des Particules, F-74941 Annecy-le-Vieux, France A. Palano Università di Bari, Dipartimento di Fisica and INFN, I-70126 Bari, Italy G. P. Chen, J. C. Chen, N. D. Qi, G. Rong, P. Wang, Y. S. Zhu Institute of High Energy Physics, Beijing 100039, China G. Eigen, P. L. Reinertsen, B. Stugu University of Bergen, Inst. of Physics, N-5007 Bergen, Norway B. Abbott, G. S. Abrams, A. W. Borgland, A. B. Breon, D. N. Brown, J. Button-Shafer, R. N. Cahn, A. R. Clark, M. S. Gill, A. V. Gritsan, Y. Groysman, R. G. Jacobsen, R. W. Kadel, J. Kadyk, L. T. Kerth, S. Kluth, Yu. G. Kolomensky, J. F. Kral, C. LeClerc, M. E. Levi, T. Liu, G. Lynch, A. B. Meyer, M. Momayezi, P. J. Oddone, A. Perazzo, M. Pripstein, N. A. Roe, A. Romosan, M. T. Ronan, V. G. Shelkov, A. V. Telnov, W. A. Wenzel Lawrence Berkeley National Laboratory and University of California, Berkeley, CA 94720, USA P. G. Bright-Thomas, T. J. Harrison, C. M. Hawkes, D. J. Knowles, S. W. O’Neale, R. C. Penny, A. T. Watson, N. K. Watson University of Birmingham, Birmingham, B15 2TT, United Kingdom T. Deppermann, K. Goetzen, H. Koch, J. Krug, M. Kunze, B. Lewandowski, K. Peters, H. Schmuecker, M. Steinke Ruhr Universität Bochum, Institut für Experimentalphysik 1, D-44780 Bochum, Germany J. C. Andress, N. R. Barlow, W. Bhimji, N. Chevalier, P. J. Clark, W. N. Cottingham, N. De Groot, N. Dyce, B. Foster, J. D. McFall, D. Wallom, F. F. Wilson University of Bristol, Bristol BS8 1TL, United Kingdom K. Abe, C. Hearty, T. S. Mattison, J. A. McKenna, D. Thiessen University of British Columbia, Vancouver, BC, Canada V6T 1Z1 S. Jolly, A. K. McKemey, J. Tinslay Brunel University, Uxbridge, Middlesex UB8 3PH, United Kingdom V. E. Blinov, A. D. Bukin, D. A. Bukin, A. R. Buzykaev, V. B. Golubev, V. N. Ivanchenko, A. A. Korol, E. A. Kravchenko, A. P. Onuchin, A. A. Salnikov, S. I. Serednyakov, Yu. I. Skovpen, V. I. Telnov, A. N. Yushkov Budker Institute of Nuclear Physics, Novosibirsk 630090, Russia D. Best, A. J. Lankford, M. Mandelkern, S. McMahon, D. P. Stoker University of California at Irvine, Irvine, CA 92697, USA A. Ahsan, K. Arisaka, C. Buchanan, S. Chun University of California at Los Angeles, Los Angeles, CA 90024, USA