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Register a new userSearch for CP violation in the decays $D^+_{(s)} to K_S^0pi^+$ and $D^+_{(s)} to K_S^0K^+$
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We have searched for CP violation in the charmed meson decays $D^{+}_{(s)}to K^0_Spi^+$ and $D^{+}_{(s)}to K^0_S K^+$ using 673 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. No evidence for CP violation is observed. We report the most sensitive CP asymmetry measurements to date for these decays: $A_{CP}^{D^+to K^0_Spi^+}=(-0.71pm0.19pm0.20)%$, $A_{CP}^{D^+_sto K^0_Spi^+}=(+5.45pm2.50pm0.33)%$, $A_{CP}^{D^+to K^0_S K^+}=(-0.16pm0.58pm0.25)%$, and $A_{CP}^{D^+_sto K^0_S K^+}=(+0.12pm0.36pm0.22)%$, where the first uncertainties are statistical and the second are systematic.
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A search for charge-parity ($CP$) violation in Cabibbo-suppressed $D_s^+to K_S^0 pi^+$, $D^+to K_S^0 K^+$ and $D^+to phi pi^+$ decays is reported using proton-proton collision data, corresponding to an integrated luminosity of 3.8 fb$^{-1}$, collected at a center-of-mass energy of 13 TeV with the LHCb detector. High-yield samples of kinematically and topologically similar Cabibbo-favored $D_{(s)}^+$ decays are analyzed to subtract nuisance asymmetries due to production and detection effects, including those induced by $CP$ violation in the neutral kaon system. The results are begin{align*} mathcal{A}_{CP}(D_s^+to K_S^0 pi^+) &=left(phantom{-}1.3phantom{0}pm1.9phantom{0}pm0.5phantom{0}right)times10^{-3}, mathcal{A}_{CP}(D^+to K_S^0 K^+) &=left(-0.09pm0.65pm0.48right)times10^{-3}, mathcal{A}_{CP}(D^+to phi pi^+) &=left(phantom{-}0.05pm0.42pm0.29right)times10^{-3}, end{align*} where the first uncertainties are statistical and the second systematic. They are the most precise measurements of these quantities to date, and are consistent with $CP$ symmetry.
The first measurements of the coherence factor R_{K_S^0Kpi} and the average strong--phase difference delta^{K_S^0Kpi} in D^0 to K_S^0 K^mppi^pm decays are reported. These parameters can be used to improve the determination of the unitary triangle angle gamma in B^- rightarrow $widetilde{D}K^-$ decays, where $widetilde{D}$ is either a D^0 or a D^0-bar meson decaying to the same final state, and also in studies of charm mixing. The measurements of the coherence factor and strong-phase difference are made using quantum-correlated, fully-reconstructed D^0D^0-bar pairs produced in e^+e^- collisions at the psi(3770) resonance. The measured values are R_{K_S^0Kpi} = 0.70 pm 0.08 and delta^{K_S^0Kpi} = (0.1 pm 15.7)$^circ$ for an unrestricted kinematic region and R_{K*K} = 0.94 pm 0.12 and delta^{K*K} = (-16.6 pm 18.4)$^circ$ for a region where the combined K_S^0 pi^pm invariant mass is within 100 MeV/c^2 of the K^{*}(892)^pm mass. These results indicate a significant level of coherence in the decay. In addition, isobar models are presented for the two decays, which show the dominance of the K^*(892)^pm resonance. The branching ratio {B}(D^0 rightarrow K_S^0K^+pi^-)/{B}(D^0 rightarrow K_S^0K^-pi^+) is determined to be 0.592 pm 0.044 (stat.) pm 0.018 (syst.), which is more precise than previous measurements.
We report a measurement of ${D^{0}}$-${overline{D}{}^{0}}$ mixing parameters and a search for indirect $CP$ violation through a time-dependent amplitude analysis of ${D^0to K_S^0pi^+pi^-}$ decays. The results are based on 921~fb$^{-1}$ of data accumulated with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. Assuming $CP$ conservation, we measure the mixing parameters $x=(0.56pm0.19^{+0.03}_{-0.09}{^{+0.06}_{-0.09}})%$ and $y=(0.30pm0.15^{+0.04}_{-0.05}{^{+0.03}_{-0.06})}%$, where the errors are statistical, experimental systematic, and systematic due to the amplitude model, respectively. With $CP$ violation allowed, the parameters $|q/p|=0.90^{+0.16}_{-0.15}{^{+0.05}_{-0.04}}{^{+0.06}_{-0.05}}$ and $arg(q/p)=(-6pm11{pm3}{^{+3}_{-4}})^{circ}$ are found to be consistent with conservation of $CP$ symmetry in mixing and in the interference between mixing and decay, respectively.
A search for non-resonant D+(s) to pi+mu+mu- and D+(s) to pi-mu+mu+ decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 1.0 fb-1, at sqrt(s) = 7 TeV recorded by the LHCb experiment in 2011. No signals are observed and the 90% (95%) confidence level (CL) limits on the branching fractions are B(D+ to pi+mu+mu-) < 7.3 (8.3) x 10-8, B(Ds+ to pi+mu+mu-) < 4.1 (4.8) x 10-7, B(D+ to pi-mu+mu+) < 2.2 (2.5) x 10-8, B(Ds+ to pi-mu+mu+) < 1.2 (1.4) x 10-7. These limits are the most stringent to date.
Based on an $e^{+}e^{-}$ collision data sample corresponding to an integrated luminosity of 2.93 $mathrm{fb}^{-1}$ collected with the BESIII detector at $sqrt{s}=3.773 mathrm{GeV}$, the first amplitude analysis of the singly Cabibbo-suppressed decay $D^{+}to K^+ K_S^0 pi^0$ is performed. From the amplitude analysis, the $K^*(892)^+ K_S^0$ component is found to be dominant with a fraction of $(57.1pm2.6pm4.2)%$, where the first uncertainty is statistical and the second systematic. In combination with the absolute branching fraction $mathcal{B}(D^+to K^+ K_S^0 pi^0)$ measured by BESIII, we obtain $mathcal{B}(D^+to K^*(892)^+ K_S^0)=(8.69pm0.40pm0.64pm0.51)times10^{-3}$, where the third uncertainty is due to the branching fraction $mathcal{B}(D^+to K^+ K_S^0 pi^0)$. The precision of this result is significantly improved compared to the previous measurement.
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