CP-violating Signals in the First-round Experiments of a B-meson Factory

Abstract

Determination of the characteristic CP-violating quantity \sin (2\beta) should be the central goal of a B-meson factory in its first-round experiments. Except the gold-plated channels B_d\to \psi K_S and \psi K_L, three other types of B_d decays to CP eigenstates can also serve for the extraction of \sin (2\beta) in the standard model: (a) the CP-forbidden transitions (B_d\bar{B}_d)_{\Upsilon (4S)} \to (X_c K_S) (X_c K_S) and $(X_c K_L) (X_c K_L), where X_c = \psi, \psi', \eta_c, etc; (b) the decay modes B_d\to D^{(*)+}D^{(*)-} and D^{(*)0}\bar{D}^{(*)0}, whose amplitudes have simple isospin relations; and (c) the decay modes B_d\to (f_{CP})_D + (\pi^0, \rho^0, a^0_1, etc), in which f_{CP} is a CP eigenstate (such as \pi^+\pi^-, K^+K^- or K_S \pi^0) arising from either D^0 or \bar{D}^0 in the neglect of D^0-\bar{D}^0 mixing. We carry out an analysis of the CP-violating signals existing in these typical processes, without loss of the possibility that new physics might significantly affect B^0_d-\bar{B}^0_d or K^0-\bar{K}^0 mixing. We also show that the magnitude of \sin (2\beta) can be well determined, in terms of only |V_{us}|, m_d/m_s and m_u/m_c, from a variety of quark mass ansatze.