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Register a new userEvidence for CP Violation in the Decay $D^+rightarrow K^0_Spi^+$
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We observe evidence for CP violation in the decay $D^+rightarrow K^0_Spi^+$ using a data sample with an integrated luminosity of 977 fb$^{-1}$ collected by the Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. The CP asymmetry in the decay is measured to be $(-0.363pm0.094pm0.067)%$, which is 3.2 standard deviations away from zero, and is consistent with the expected CP violation due to the neutral kaon in the final state.
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We search for CP violation in the decay $D^+rightarrow K^0_S K^+$ using a data sample with an integrated luminosity of 977 fb$^{-1}$ collected with the Belle detector at the KEKB $e^+e^-$ asymmetric-energy collider. No CP violation has been observed and the CP asymmetry in $D^+rightarrow K^0_S K^+$ decay is measured to be $(-0.25pm0.28pm0.14)%$, which is the most sensitive measurement to date. After subtracting CP violation due to $K^0-bar{K}^0$ mixing, the CP asymmetry in $D^+rightarrowbar{K}^0 K^+$ decay is found to be $(+0.08pm0.28pm0.14)%$.
A measurement of direct CP violation in the decay $B^{+} rightarrow K^{+} pi^{0}$ is reported using a data sample corresponding to an integrated luminosity of 5.4 $textrm{fb}^{-1}$, collected with the LHCb experiment at a center-of-mass energy of $sqrt{s}=13$ TeV. The CP asymmetry is measured to be $0.025 pm 0.015 pm 0.006 pm 0.003$, where the uncertainties are statistical, systematic, and due to an external input, respectively. This is the most precise measurement of the CP asymmetry in the decay $B^{+} rightarrow K^{+} pi^{0}$ and exceeds the precision on the current world average. This direct CP asymmetry is a key input to studies of a long-standing anomaly in $B$ meson decays, known as the $Kpi$-puzzle. The asymmetry is consistent with the previous measurements of this quantity, confirming and significantly enhancing the observed anomalous difference between the direct CP asymmetries of the $B^{0} rightarrow K^{+} pi^{-}$ and $B^{+} rightarrow K^{+} pi^{0}$ decays.
We report a search for CP-violating asymmetry in B0 -> D*+- D-+ decays. The analysis employs two methods of B0 reconstruction: full and partial. In the full reconstruction method all daughter particles of the B0 are required to be detected; the partial reconstruction technique requires a fully reconstructed D- and only a slow pion from the D*+ -> D0 pi_slow+ decay. From a fit to the distribution of the time interval corresponding to the distance between two B meson decay points we calculate the CP-violating parameters and find the significance of nonzero CP asymmetry to be 2.7 standard deviations.
A search for CP violation in Cabibbo-suppressed $D^{pm}rightarrow K^0_{mathrm{S}} K^{pm}$ and $D^{pm}_{s}rightarrow K^0_{mathrm{S}} pi^{pm}$ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of 3~fb$^{-1}$, recorded by the LHCb experiment. The individual $CP$-violating asymmetries are measured to be begin{eqnarray*} mathcal{A}_{CP}^{D^{pm}rightarrow K^0_{mathrm{S}} K^{pm}} & = & (+0.03 pm 0.17 pm 0.14) % mathcal{A}_{CP}^{D^{pm}_{s}rightarrow K^0_{mathrm{S}} pi^{pm}} & = & (+0.38 pm 0.46 pm 0.17) %, end{eqnarray*} assuming that $CP$ violation in the Cabibbo-favoured decays is negligible. A combination of the measured asymmetries for the four decay modes $D^{pm}_{(s)}rightarrow K^0_{mathrm{S}} K^{pm}$ and $D^{pm}_{(s)}rightarrow K^0_{mathrm{S}} pi^{pm}$ gives the sum [ mathcal{A}_{CP}^{D^{pm}rightarrow K^0_{mathrm{S}} K^{pm}} + mathcal{A}_{CP}^{D^{pm}_{s}rightarrow K^0_{mathrm{S}} pi^{pm}} = (+0.41 pm 0.49 pm 0.26) %. ] In all cases, the first uncertainties are statistical and the second systematic. The results represent the most precise measurements of these asymmetries to date and show no evidence for CP violation.
We report on the observation of the $W$-annihilation decay $D^{+}_{s} rightarrow omega pi^{+}$ and the evidence for $D_{s}^{+} rightarrow omega K^{+}$ with a data sample corresponding to an integrated luminosity of 3.19 fb$^{-1}$ collected with the BESIII detector at the center-of-mass energy $sqrt{s} = 4.178$ GeV. We obtain the branching fractions $mathcal{B}(D^{+}_{s} rightarrow omega pi^{+}) = (1.77pm0.32_{{rm stat.}}pm0.11_{{rm sys.}}) times 10^{-3}$ and $mathcal{B}(D^{+}_{s} rightarrow omega K^{+}) = (0.87pm0.24_{{rm stat.}}pm0.07_{{rm sys.}}) times 10^{-3}$, respectively.
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