No Arabic abstract
The doubly Cabibbo-suppressed decay $Xi_{c}^{+}to pphi$ with $phito K^{+}K^{-}$ is observed for the first time, with a statistical significance of more than fifteen standard deviations. The data sample used in this analysis corresponds to an integrated luminosity of 2 fb$^{-1}$ recorded with the LHCb detector in $pp$ collisions at a centre-of-mass energy of 8 TeV. The ratio of branching fractions between the decay $Xi_{c}^{+}to pphi$ and the singly Cabibbo-suppressed decay $Xi_{c}^{+}to pK^{-}pi^{+}$ is measured to be begin{equation*} frac{mathcal{B}(Xi_{c}^{+}to pphi)}{mathcal{B}(Xi_{c}^{+}to pK^{-}pi^{+})} = (19.8 pm 0.7 pm 0.9 pm 0.2) times 10^{-3}, end{equation*} where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the $phito K^{+}K^{-}$ branching fraction.
We report the first observation of the doubly Cabibbo-suppressed decay $D^+_sto K^+K^+pi^-$ using 605 fb$^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching ratio with respect to its Cabibbo-favored counterpart $mathcal{B}(D^+_sto K^+K^+pi^-)$ / $mathcal{B}(D^+_sto K^+K^-pi^+)$ is (0.229$pm0.028pm$0.012)%, where the first uncertainty is statistical and the second is systematic. We also report a significantly improved measurement of the doubly Cabibbo-suppressed decay $D^+to K^+pi^+pi^-$, with a branching ratio $mathcal{B}(D^+to K^+pi^+pi^-)$ / $mathcal{B}(D^+to K^-pi^+pi^+)$=(0.569$pm0.018pm$0.014)%.
The doubly charmed baryon decay $Xi_{cc}^{++} rightarrow Xi_{c}^{+} pi^{+}$ is observed for the first time, with a statistical significance of $5.9sigma$, confirming a recent observation of the baryon in the $Lambda_c^{+} K^{-} pi^{+} pi^{+}$ final state. The data sample used corresponds to an integrated luminosity of $1.7,mathrm{fb}^{-1}$, collected by the LHCb experiment in $pp$ collisions at a center-of-mass energy of $13mathrm{,Tekern -0.1em V}$. The $Xi_{cc}^{++}$ mass is measured to be begin{equation} onumber 3620.6pm 1.5~(text{stat})pm 0.4~(text{syst}) pm 0.3~(Xi_{c}^{+})~text{MeV}/it{c}^{2}, end{equation} and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be begin{equation} onumber frac{mathcal{B} (Xi_{cc}^{++} rightarrow Xi_{c}^{+} pi^{+}) times mathcal{B}(Xi_{c}^{+} rightarrow pK^{-}pi^{+})} {mathcal{B} (Xi_{cc}^{++} rightarrow Lambda_c^{+} K^{-} pi^{+} pi^{+}) times mathcal{B}(Lambda_c^{+} rightarrow pK^{-}pi^{+})} = 0.035pm 0.009~(text{stat}) pm 0.003~(text{syst}). end{equation}
We report the first observation of the decay $Lambda^{+}_{c} rightarrow p K^{+} pi^{-}$ using a 980 $mathrm{fb^{-1}}$ data sample collected by the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider. This is the first doubly Cabibbo-suppressed decay of a charmed baryon to be observed. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be $mathcal{B}(Lambda^{+}_{c} rightarrow p K^{+} pi^{-})/mathcal{B}(Lambda^{+}_{c} rightarrow p K^{-} pi^{+})=(2.35pm0.27pm0.21)times10^{-3}$, where the uncertainties are statistical and systematic, respectively.
Using $2.93 rm fb^{-1}$ of $e^+e^-$ collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the first observation of the doubly Cabibbo-suppressed decay $D^+to K^+pi^+pi^-pi^0$ is reported. After removing decays that contain narrow intermediate resonances, including $D^+to K^+eta$, $D^+to K^+omega$, and $D^+to K^+phi$, the branching fraction of the decay $D^+to K^+pi^+pi^-pi^0$ is measured to be $(1.13 pm 0.08_{rm stat} pm 0.03_{rm syst})times 10^{-3}$. The ratio of branching fractions of $D^+to K^+pi^+pi^-pi^0$ over $D^+to K^-pi^+pi^+pi^0$ is found to be $(1.81pm0.15)$%, which corresponds to $(6.28pm0.52)tan^4theta_C$, where $theta_C$ is the Cabibbo mixing angle. This ratio is significantly larger than the corresponding ratios for other doubly Cabibbo-suppressed decays. The asymmetry of the branching fractions of charge-conjugated decays $D^pmto K^pmpi^pmpi^mppi^0$ is also determined, and no evidence of $CP$ violation is found. In addition, the first evidence of the $D^+to K^+omega$ decay, with a statistical significance of 3.3$sigma$, is presented and its decay branching fraction is determined to be $({5.7^{+2.5}_{-2.1}}_{rm stat}pm0.2_{rm syst})times10^{-5}$.
Using an $e^+e^-$ annihilation data sample corresponding to an integrated luminosity of $2.93,rm fb^{-1}$ collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, the doubly Cabibbo-suppressed decay $D^+to K^+pi^+pi^-pi^0$ is studied with a semileptonic tag method. After removing the decays containing narrow intermediate resonances, $D^+to K^+eta$, $D^+to K^+omega$, and $D^+to K^+phi$, the branching fraction for the decay $D^+to K^+pi^+pi^-pi^0$ is determined to be $(1.03 pm 0.12_{rm stat} pm 0.06_{rm syst})times 10^{-3}$. The ratio of the branching fraction for $D^+to K^+pi^+pi^-pi^0$ to its Cabibbo-favored counterpart $D^+to K^-pi^+pi^+pi^0$ is measured to be $ (1.65pm0.21)%$, corresponding to $(5.73pm0.73)tan^4theta_C$, where $theta_C$ is the Cabibbo mixing angle. These results are consistent with our previous measurement with hadronic tags but are significantly larger than other doubly Cabibbo-suppressed decays in the charm sector.