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Register a new userUpdated Measurement of the Strong Phase in D0 --> K+pi- Decay Using Quantum Correlations in e+e- --> D0 D0bar at CLEO
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We analyze a sample of 3 million quantum-correlated D0 D0bar pairs from 818 pb^-1 of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV, to give an updated measurement of cosdelta and a first determination of sindelta, where delta is the relative strong phase between doubly Cabibbo-suppressed D0 --> K+pi- and Cabibbo-favored D0bar --> K+pi- decay amplitudes. With no inputs from other experiments, we find cosdelta = 0.81 +0.22+0.07 -0.18-0.05, sindelta = -0.01 +- 0.41 +- 0.04, and |delta| = 10 +28+13 -53-0 degrees. By including external measurements of mixing parameters, we find alternative values of cosdelta = 1.15 +0.19+0.00 -0.17-0.08, sindelta = 0.56 +0.32+0.21 -0.31-0.20, and delta = (18 +11-17) degrees. Our results can be used to improve the world average uncertainty on the mixing parameter y by approximately 10%.
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We exploit the quantum coherence between pair-produced D0 and D0bar in psi(3770) decays to study charm mixing, which is characterized by the parameters x and y, and to make a first determination of the relative strong phase delta between doubly Cabibbo-suppressed D0 -> K+pi- and Cabibbo-favored D0bar -> K+pi-. We analyze a sample of 1.0 million D0D0bar pairs from 281 pb^-1 of e+e- collision data collected with the CLEO-c detector at E_cm = 3.77 GeV. By combining CLEO-c measurements with branching fraction input and time-integrated measurements of R_M = (x^2+y^2)/2 and R_{WS} = Gamma(D0 -> K+pi-)/Gamma(D0bar -> K+pi-) from other experiments, we find cosdelta = 1.03 +0.31-0.17 +- 0.06, where the uncertainties are statistical and systematic, respectively. In addition, by further including external measurements of charm mixing parameters, we obtain an alternate measurement of cosdelta = 1.10 +- 0.35 +- 0.07, as well as xsindelta = (4.4 +2.7-1.8 +- 2.9) x 10^-3 and delta = 22 +11-12 +9-11 degrees.
Measurements of charm mixing parameters from the decay-time-dependent ratio of D0->K+pi- to D0->K-pi+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb^{-1} of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP) symmetry, the mixing parameters are determined to be x^2=(5.5 +- 4.9)x10^{-5}, y= (4.8 +- 1.0)x10^{-3}, and R_D=(3.568 +- 0.066)x10^{-3}. Allowing for CP violation, the mixing parameters are determined separately for D0 and D0bar mesons yielding A_D = (-0.7 +- 1.9)%, for the direct CP-violating asymmetry, and 0.75 < |q/p|< 1.24 at the 68.3% confidence level, where q and p are parameters that describe the mass eigenstates of the neutral charm mesons in terms of the flavor eigenstates. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.
The D0 meson can decay to the wrong sign K+pi- state either through a doubly Cabibbo suppressed decay or via mixing to the D0bar state followed by the Cabibbo favoured decay D0bar -> K+ pi-. We measure the rate of wrong sign decays relative to the Cabibbo favoured decay to (0.383 +- 0.044 +- 0.022)% and give our sensitivity to a mixing signal.
A measurement of the rate for the wrong-sign decay D0 -> K+ pi- pi+ pi- relative to that for the right-sign decay D0 -> K- pi+ pi+ pi- is presented. Using 791 fb-1 of data collected with the Belle detector, we obtain a branching fraction ratio of R_WS = [0.324 +- 0.008 (stat) +- 0.007 (sys)]%. Multiplying this ratio by the world average value for the branching fraction B(D0 -> K- pi+ pi+ pi-) gives a branching fraction B(D0 -> K+ pi- pi+ pi-) = (2.61 +- 0.06 +0.09 -0.08) x 10-4.
Measurements of the coherence factors (R_Kpipi0 and R_K3pi) and the average strong-phase differences (delta^Kpipi0_D and delta^K3pi_D) for the decays D0-> K-pi+pi0 and D0->K-pi+pi+pi- are presented. These parameters are important inputs to the determination of the unitarity triangle angle gamma in B+/- -> DK+/- decays, where D designates a D0 or D0bar meson decaying to a common final state. The measurements are made using quantum correlated DDbar decays collected by the CLEO-c experiment at the psi(3770) resonance, and augment a previously published analysis by the inclusion of new events in which the signal decay is tagged by the mode D-> K0Spi+pi-. The measurements also benefit from improved knowledge of external inputs, namely the D0D0bar mixing parameters, r_D^Kpi and several D-meson branching fractions. The measured values are R_Kpipi0 = 0.82 +- 0.07, delta_D^Kpipi0 = (164+20-14) deg., R_K3pi = 0.32+0.20-0.28 and delta^K3pi_D = (225+21_-78) deg. Consideration is given to how these measurements can be improved further by using the larger quantum-correlated data set collected by BESIII.
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