Measurement of CP violation observables and parameters for the decays B^± → DK^(*±)

Abstract

We study the decay B^- → DK^(*-) using a sample of 379 × 10^6 Υ(4S) → BB(overbar) events collected with the BABAR detector at the PEP-II B factory. We perform a Gronau-London-Wyler analysis where the D meson decays into either a CP-even (CP+) eigenstate (K^+K^-, π^+π^-), CP-odd (CP-) eigenstate (K(^0_S)π^0, K(^0_S)ϕ, K(^0_S)ω) or a non-CP state (KT-π^+). We also analyze D meson decays into K^+π^- from a Cabibbo-favored D(overbar)^0 decay or doubly suppressed D^0 decay [Atwood-Dunietz-Soni (ADS) analysis]. We measure observables that are sensitive to the Cabibbo-Kobayashi-Maskawa angle γ: the partial-rate charge asymmetries A_(CP±), the ratios R_(CP±) of the B-decay branching fractions in CP± and non-CP decay, the ratio R_(ADS) of the charge-averaged branching fractions, and the charge asymmetry A_(ADS) of the ADS decays: A_(CP+) = 0.09±0.13±0.06, A_(CP-) = -0.23±0.21±0.07, R_(CP+) = 2.17±0.35±0.09, R_(CP-) = 1.03±0.27±0.13, R_(ADS) = 0.066±0.031±0.010, and A_(ADS) = -0.34±0.43±0.16, where the first uncertainty is statistical and the second is systematic. Combining all the measurements and using a frequentist approach yields the magnitude of the ratio between the Cabibbo-suppressed and favored amplitudes, r_B = 0.31 with a one (two) sigma confidence level interval of [0.24, 0.38] ([0.17, 0.43]). The value r_ B = 0 is excluded at the 3.3 sigma level. A similar analysis excludes values of γ in the intervals [0, 7]°, [55, 111]°, and [175, 180]° ([85, 99]°) at the one (two) sigma confidence level.

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