Grossman, YPeláez Sagredo, José RamónWorah, M. P.2023-06-202023-06-201998-11-010556-282110.1103/PhysRevD.58.096009https://hdl.handle.net/20.500.14352/60095©1998 The American Physical Society. The authors thank Y. Nir, S. Plaszczynski, H. Quinn, T. Rizzo, J. Rosner, M-H. Schune, A. Snyder and A. Soffer for useful conversations. J.R.P. has been partially supported by the Spanish CICYT under contract AEN93-0776, and thanks the SLAC Theory Group for their kind hospitality as well as the Spanish Ministerio de Educación y Cultura for financial support. This research was supported by the Department of Energy under contract DE-AC03-76SF00515.B flavor tagging will be extensively studied at the asymmetric B factories due to its importance in CP asymmetry measurements. The primary tagging modes are the semileptonic decays of the b (lepton tag), or the hadronic b → c(→ s) decays (kaon tag). We suggest that looking for time dependent CP asymmetries in events where one B is tagged leptonically and the other one is tagged with a kaon could result in an early detection of CP violation. Although in the standard model these asymmetries are expected to be small, 1%, they could be measured with about the same amount of data as in the "gold-plated" decay B_d→ψ K_s. In the presence of physics beyond the standard model, these asymmetries could be as large as 5%, and the first CP violation signal in the B system may show up in these events. We give explicit examples of new physics scenarios where this occurs. [S0556-2821(98)09321-7]engjournal articlehttp://dx.doi.org/10.1103/PhysRevD.58.096009http://journals.aps.orgopen access51-73Astronomy & astrophysicsPhysicsparticles & fieldsFísica-Modelos matemáticosFísica matemática