77 research outputs found

    CP Asymmetries in (Semi-)Inclusive B0 Decays

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    It was recently pointed out that inclusive B^0(t) decays could show CP violation. The totally inclusive asymmetry is expected to be tiny [O(10^{-3})] because of large cancellations among the asymmetries in the charmless, single charm and double charm final states. Enriching particular final state configurations could significantly increase the CP-asymmetry and observability. Such studies can extract fundamental CKM (Cabibbo-Kobayashi-Maskawa) parameters, and (perhaps) even Delta m(B_s). A superb vertex detector could see CP violation with 10^5 (10^6) flavor-tagged B_s (B_d) mesons within the CKM model. Because the effects could be significantly larger due to new physics, they should be searched for in existing or soon available data samples.Comment: RevTex, 20 pages, no figure

    Resolving a Discrete Ambiguity in the CKM Angle β\beta through Bu,dJ/ψKB_{u,d} \to J/\psi K^\ast and BsJ/ψϕB_s \to J/\psi \phi Decays

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    It is well known that sin(2β)\sin(2\beta), where β\beta is one of the angles of the unitarity triangle of the CKM matrix, can be determined in a theoretically clean way by measuring mixing-induced CP violation in the decay BdJ/ψKSB_d \to J/\psi K_S. Another clean extraction of this CKM angle is provided by the time-dependent angular distribution for the decay products of BdJ/ψ(l+l)K0(π0KS)B_d \to J/\psi(\to l^+l^-) K^{\ast0}(\to \pi^0 K_S), where we have more observables at our disposal than in the case of BdJ/ψKSB_d \to J/\psi K_S, so that in addition to sin(2β)\sin(2\beta) also cos(2β)\cos(2\beta) can be probed in a direct way. Unfortunately a sign ambiguity remains in cos(2β)\cos(2\beta). If it could be resolved, a discrete ambiguity in the extraction of the CKM angle β\beta could be resolved as well, which would allow a more incisive test of the CKM model of CP violation. This note shows that detailed time-dependent studies of Bu,dJ/ψKB_{u,d} \to J/\psi K^{\ast} and BsJ/ψϕB_s \to J/\psi \phi decay processes can determine the sign of cos(2β)\cos(2\beta), thereby removing the corresponding ambiguity in the extraction of the CKM angle β\beta.Comment: 5 pages, LaTeX, no figure

    Clean CKM Information from Bd(t) -> D(*)+/- pi-/+

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    It has been known for many years that the Bd(t) -> D(*)+/- {pi-/+, rho-/+, a1-/+} modes may involve observable CP violating effects. This note describes how to determine cleanly the Cabibbo-Kobayashi-Maskawa (CKM) phase phi = -2 beta - gamma = -pi + alpha - beta, even in the presence of possible final state interactions. A discrete ambiguity remains.Comment: 8 pages, revte

    Beautiful CP Violation

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    CP violation is observed to date only in K^0 decays and is parameterizable by a single quantity epsilon. Because it is one of the least understood phenomena in the Standard Model and holds a clue to baryogenesis, it must be investigated further. Highly specialized searches in K^0 decays are possible. Effects in B decays are much larger. In addition to the traditional B_d -> J/\psi K_S, pi^+pi^- asymmetries, CP violation could be searched for in already existing inclusive B data samples. The rapid B_s - B_s.bar oscillations cancel in untagged B_s data samples, which therefore allow feasibility studies for the observation of CP violation and the extraction of CKM elements with present vertex detectors. The favored method for the extraction of the CKM angle gamma is shown to be unfeasible and a solution is presented involving striking direct CP violation in charged B decays. Novel methods for determining the B_s mixing parameter Delta m are described without the traditional requirement of flavor-specific final states.Comment: 11 pages, latex, 2 postscript figures included, talk presented at the b20 conference, June 29 - July 2, 1997, IIT, Chicag

    Enhanced CP Violation with BKD0(D0)B\to K D^0 (\overline D^0) Modes and Extraction of the CKM Angle gamma

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    The Gronau-London-Wyler (GLW) method extracts the CKM angle γ\gamma by measuring B±B^\pm decay rates involving D0/D0D^0/\overline D^0 mesons. Since that method necessitates the interference between two amplitudes that are significantly different in magnitude, the resulting asymmetries tend to be small. CP violation can be greatly enhanced for decays to final states that are common to both D^0 and D0\overline D^0 and that are not CP eigenstates. In particular, large asymmetries are possible for final states f such that D0fD^0\to f is doubly Cabibbo suppressed while D0f\overline D^0\to f is Cabibbo allowed. The measurement of interference effects in two such modes allows the extraction of γ\gamma without prior knowledge of Br(BKD0)Br(B^-\to K^- \overline D^0), which may be difficult to determine due to backgrounds.Comment: 12 pages, LaTeX, no figure
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