No Arabic abstract
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.
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.
Measurements on the weak decay asymmetry parameters of charmed baryon, say $Xi_c$, provide more information on the $W$-emission and $W$-exchange mechanisms controlled by the strong and weak interactions. Taking advantage of the spin polarization in the charmed baryon decays, we investigate the possibility to measure the weak decay asymmetry parameters in the $e^{+}e^{-}to Xi_c^0barXi_c^0$ process. We analyze the transverse polarization spontaneously produced in this process and spin transfer in the subsequent $Xi_c$ decays. The sensitivity to measure the asymmetry parameters are estimated for the decay $Xi_ctoXi pi$.
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.
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.
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.