Measurement of the rare decay 0 !

E. Abouzaid, M. Arenton, A. R. Barker,* L. Bellantoni, A. Bellavance, E. Blucher, G. J. Bock, E. Cheu, R. Coleman, M. D. Corcoran, B. Cox, A. R. Erwin, C. O. Escobar, A. Glazov, A. Golossanov, R. A. Gomes, P. Gouffon, K. Hanagaki, Y. B. Hsiung, H. Huang, D. A. Jensen, R. Kessler, K. Kotera, A. Ledovskoy, P. L. McBride, E. Monnier, K. S. Nelson, H. Nguyen, R. Niclasen, D. G. Phillips II, H. Ping, X. R. Qi, E. J. Ramberg, R. E. Ray, M. Ronquest, E. Santos, J. Shields, W. Slater, D. Smith, N. Solomey, E. C. Swallow, P. A. Toale, R. Tschirhart, C. Velissaris, Y. W. Wah, J. Wang, H. B. White, J. Whitmore, M. J. Wilking, B. Winstein, R. Winston, E. T. Worcester, M. Worcester, T. Yamanaka, E. D. Zimmerman, and R. F. Zukanovich University of Arizona, Tucson, Arizona 85721, USA University of California at Los Angeles, Los Angeles, California 90095, USA Universidade Estadual de Campinas, Campinas, Brazil 13083-970 The Enrico Fermi Institute, The University of Chicago, Chicago, Illinois 60637, USA University of Colorado, Boulder, Colorado 80309, USA Elmhurst College, Elmhurst, Illinois 60126, USA Fermi National Accelerator Laboratory, Batavia, Illinois 60510, USA Osaka University, Toyonaka, Osaka 560-0043 Japan Rice University, Houston, Texas 77005, USA Universidade de São Paulo, São Paulo, Brazil 05315-970 The Department of Physics and Institute of Nuclear and Particle Physics, University of Virginia, Charlottesville, Virginia 22901, USA University of Wisconsin, Madison, Wisconsin 53706, USA (Received 24 October 2006; published 11 January 2007)