No Arabic abstract
Based on 2.93 fb$^{-1}$ $e^+e^-$ collision data taken at center-of-mass energy of 3.773 GeV by the BESIII detector, we report searches for the singly Cabibbo-suppressed decays $D^{+}toomegapi^{+}$ and $D^{0}toomegapi^{0}$. A double tag technique is used to measure the absolute branching fractions $mathcal{B}(D^{+}toomegapi^{+})=(2.79pm0.57pm0.16)times 10^{-4}$ and $mathcal{B}(D^{0}toomegapi^{0})=(1.17pm0.34pm0.07)times 10^{-4}$, with statistical significances of $5.5sigma$ and $4.1sigma$, respectively. We also present measurements of the absolute branching fractions for the related $eta pi$ decay modes. We find $mathcal{B}(D^{+}toetapi^{+})=(3.07pm0.22pm0.13)times10^{-3}$ and $mathcal{B}(D^{0}toetapi^{0})=(0.65pm0.09pm0.04)times10^{-3}$, which are consistent with the current world averages. The first and second 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 $({5.7^{+2.5}_{-2.1}}_{rm stat}pm0.2_{rm syst})times10^{-5}$.
We have searched for mixing in the D0-D0bar system by measuring the decay-time distribution of D0->K+pi- decays. The analysis uses 90 fb^{-1} of data collected by the Belle detector at the KEKB e+e- collider. We fit the decay-time distribution for the mixing parameters x and y and also for the parameter R_D, which is the ratio of the rate for the doubly-Cabibbo-suppressed decay D0->K+pi- to that for the Cabibbo-favored decay D0->K-pi+. We do these fits both assuming CP conservation and allowing for CP violation. We use a frequentist method to obtain a 95% C.L. region in the x^2 - y plane. Assuming no mixing, we measure R_D = (0.381 pm 0.017 +0.008 -0.016) %.
Using a data sample of $e^+e^-$ collision data corresponding to an integrated luminosity of 2.93 $fb^{-1}$ collected with the BESIII detector at a center-of-mass energy of $sqrt{s}= 3.773~GeV$,we search for the singly Cabibbo-suppressed decays $D^{0}topi^{0}pi^{0}pi^{0}$, $pi^{0}pi^{0}eta$, $pi^{0}etaeta$ and $etaetaeta$ using the double tag method. The absolute branching fractions are measured to be $mathcal{B}(D^{0}topi^{0}pi^{0}pi^{0}) = (2.0 pm 0.4 pm 0.3)times 10^{-4}$, $mathcal{B}(D^{0}topi^{0}pi^{0}eta) = (3.8 pm 1.1 pm 0.7)times 10^{-4}$ and $mathcal{B}(D^{0}topi^{0}etaeta) = (7.3 pm 1.6 pm 1.5)times 10^{-4}$ with the statistical significances of $4.8sigma$, $3.8sigma$ and $5.5sigma$, respectively, where the first uncertainties are statistical and the second ones systematic. No significant signal of $D^{0}toetaetaeta$ is found, and the upper limit on its decay branching fraction is set to be $mathcal{B}(D^{0}toetaetaeta) < 1.3 times 10^{-4}$ at the $90%$ confidence level.
Using a data sample corresponding to 13.7 fb^-1 collected with the CLEO II and II.V detectors, we report new branching fraction measurements for two Cabibbo-suppressed decay modes of the D^+ meson: Br(D^+ to pi^+ pi^0) = (1.3 +/- 0.2) x 10^-3 and Br(D^+ to bar{K}^0 K^+) = (5.2 +/- 0.6) x 10^-3 which are significant improvements over past measurements. The errors include statistical and systematical uncertainties as well as the uncertainty in the absolute D^+ branching fraction scale. We also set the first 90% confidence level upper limit on the branching fraction of the doubly Cabibbo-suppressed decay mode Br(D^+ to K^+ pi^0) < 4.2 x 10^-4.
We study the singly-Cabibbo-suppressed decays $Lambda_c^{+}to peta$ and $Lambda_{c}^{+}to ppi^{0}$ using $Lambda_{c}^{+}Lambda_{c}^{+}$ pairs produced by $e^+e^-$ collisions at a center-of-mass energy of $sqrt{s} = 4.6; GeV$. The data sample was collected by the BESIII detector at the BEPCII collider and corresponds to an integrated luminosity of 567 $pb^{-1}$. We find the first evidence for the decay $Lambda_{c}^{+}to p eta$ with a statistical significance of $4.2sigma$ and measure its branching fraction to be $mathcal{B}(Lambda_c^+to peta)= (1.24pm0.28({rm{stat.}})pm0.10({rm{syst.}}))times10^{-3}$. No significant $Lambda_c^+ to ppi^0$ signal is observed. We set an upper limit on its branching fraction $mathcal{B}(Lambda_c^+ to ppi^{0}) < 2.7 times 10^{-4}$ at the 90% confidence level.