22-28 July 2010
Palais des Congrès de Paris
Europe/Paris timezone

Measurements of the CKM angle gamma at BABAR

23 Jul 2010, 16:15
Salle 242A ()

Salle 242A

Parallel Session Talk 06 - CP violation, CKM and Rare Decays 06 - CP violation, CKM and Rare Decays


Fernando Martinez-Vidal (Universidad de Valencia)


Using data from approximately 470 million B-Bbar pair events collected with the BaBar detector at SLAC's PEP-II e+e- B-factory running on the Upsilon(4S), we have made a number of measurements that are sensitive to the Cabibbo-Kobayashi-Maskawa CP-violating angle gamma. These include a measurement of gamma from a Dalitz Plot analysis of neutral D meson decays to K^0_S pi^+ pi^- and K^0_SK^+K^- produced in the processes B^(-+) --> D K^(-+), B^(-+) --> D^{*} K^(-+) with D^{*} --> D pi^0,D gamma, and B^(-+) --> DK^{*-+} with K^{* -+} --> K_S^0 \pi^(-+). We also search for b --> u transitions in B^- --> D^0K^- and B^- --> D^{*0} K^- decays which are sensitive gamma due to interference between the b --> c transition B^- --> D^{(*)0}K^- followed by the doubly Cabibbo-suppressed decay D^0 --> K^+ pi^-, and the b --> u transition B^- --> D^{(*)0}K^- followed by the Cabibbo-favored decay anti-{D}^0 --> K^+ pi^-. We also analyze the decay B^- --> D^{(*)} pi^- with the D decaying into the doubly Cabibbo-suppressed mode D --> K^+\pi^-. In addition we report on a measurement of the gamma in B^(+-)--> D_CP K^(+-) decays: from reconstructed B^(+-) --> D K^(+-) decays, where the neutral D meson is reconstructed in both CP-eigenstate and non-CP-eigenstate final states, we measure the partial rate charge asymmetries for CP-even and CP-odd D final states and the ratios between the charge-averaged B^(+-) --> D K^(+-) decay partial rates, where the D meson decays to CP and non-CP eigenstates. We infer frequentist confidence intervals for gamma, for the strong phase delta_B, and for the amplitude ratio r_B, which are related to the B^(+-)-->DK^(+-) decay amplitudes by r_Be^{i(\delta_B-\gamma)} = A(B^- --> \overline{D^0} K^-)/A(B^- --> D^0 K^-).We also report on the study of the decay B^- --> D^{0} (\overline D^{0}) K^-, where the D^0 or \overline D^{0} decay to K^+ pi^- pi^0. We measure the ratios of the suppressed to favored branching fractions as well as the CP asymmetries of those modes. Since the amplitudes for the processes B^+--> \overline D^{0} K^+ and B^+ --> D^{0} K^+ are proportional to V_{cb} and V_{ub}, respectively, these decays are sensitive to the weak phase gamma as well as to the magnitude r_B of the ratio between the two amplitudes. Finally, we report on the results of a search for the decays B^+ --> D^{+} K^{(*)0}.

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