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Register a new userMeasurement of CP asymmetry in Cabibbo suppressed D0 decays
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We measure the CP-violating asymmetries in decays to the D0 -> K+K- and D0 -> pi+pi- CP eigenstates using 540 fb^{-1} of data collected with the Belle detector at or near the Upsilon(4S) resonance. Cabibbo-favored D0 -> K-pi+ decays are used to correct for systematic detector effects. The results, A_{CP}^{KK} = (-0.43 +- 0.30 +- 0.11)% and A_{CP}^{pipi} = (+0.43 +- 0.52 +- 0.12)%, are consistent with no CP violation.
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Using 2.93 fb$^{-1}$ of $e^{+}e^{-}$ collision data taken at a center-of-mass energy of 3.773 GeV by the BESIII detector at the BEPCII, we measure the branching fractions of the singly Cabibbo-suppressed decays $D to omega pi pi$ to be $mathcal{B}(D^0 to omega pi^+pi^-) = (1.33 pm 0.16 pm 0.12)times 10^{-3}$ and $mathcal{B}(D^+ to omega pi^+pi^0) =(3.87 pm 0.83 pm 0.25)times 10^{-3}$, where the first uncertainties are statistical and the second ones systematic. The statistical significances are $12.9sigma$ and $7.7 sigma$, respectively. The precision of $mathcal{B}(D^0 to omega pi^+pi^-)$ is improved by a factor of 2.1 over the CLEO measurement, and $mathcal{B}(D^+ to omega pi^+pi^0)$ is measured for the first time. No significant signal of $mathcal{B}(D^0 to omega pi^0pi^0)$ is observed, and the upper limit on the branching fraction is $mathcal{B}(D^0 to omega pi^0pi^0) < 1.10 times 10^{-3}$ at the $90%$ confidence level. The branching fractions of $Dto eta pi pi$ are also measured and consistent with existing results.
We report on a search for direct CP asymmetry in the singly Cabibbo-suppressed decay D+- --> K+ K- pi+- using a data sample of 476 fb-1 accumulated with the BaBar detector running at and just below the Y(4S) resonance. The CP-violating decay rate asymmetry A_CP is determined to be (0.35 +- 0.30 +- 0.15)%. Model-dependent and model-independent Dalitz plot analysis techniques are used to search for CP-violating asymmetries in the various intermediate states.
We report the first observation of the Cabibbo-suppressed decays $Xi_c^0rightarrow Xi^- K^+$, $Xi_c^0raLambda K^+ K^-$ and $Xi_c^0rightarrow Lambda phi$, using a data sample of $711, mathrm{fb}^{-1}$ collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. We measure the ratios of branching fractions to be $frac{{cal B}(Xi_c^0ra Xi^- K^+)}{{cal B}(Xi^0_craXi^-pi^+)}=(2.75pm 0.51pm 0.25)times 10^{-2}$, $frac{{cal B}(Xi_c^0raLambda K^+ K^-)}{{cal B}(Xi_c^0rightarrowXi^- pi^+)}=(2.86pm 0.61pm 0.24)times 10^{-2}$ and $frac{{cal B}(Xi_c^0ra Lambdaphi)}{{cal B}(Xi^0_craXi^-pi^+)}=(3.43pm 0.58pm 0.32)times 10^{-2}$, where the first uncertainty is statistical and the second is systematic.
A measurement of the time-integrated $CP$ asymmetry in the Cabibbo-suppressed decay $D^0rightarrow K^-K^+$ is performed using pp collision data, corresponding to an integrated luminosity of 3fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The flavour of the charm meson at production is determined from the charge of the pion in $D^{*+}rightarrow D^0 pi^+$ and $D^{*-}rightarrow bar{D^0} pi^-$ decays. The time-integrated $CP$ asymmetry $A_{CP}(K^-K^+)$ is obtained assuming negligible $CP$ violation in charm mixing and in Cabibbo-favoured $D^0rightarrow K^-pi^+$, $D^+rightarrow K^-pi^+pi^+$ and $D^+rightarrow bar{K^0}pi^+$ decays used as calibration channels. It is found to be $A_{CP}(K^-K^+)=(0.14pm0.15(stat)pm0.10(syst))%$. A combination of this result with previous LHCb measurements yields $A_{CP}(K^-K^+)=(0.04pm0.12(stat)pm0.10(syst))%$, $A_{CP}(pi^-pi^+)=(0.07pm0.14(stat)pm0.11(syst))%$. These are the most precise measurements from a single experiment. The result for $A_{CP}(K^-K^+)$ is the most precise determination of a time-integrated $CP$ asymmetry in the charm sector to date, and neither measurement shows evidence of CP asymmetry.
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.
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