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.
The decay $D^{+}_{s}rightarrow pi^{+}pi^{+}pi^{-}eta$ is observed for the first time, using $e^+e^-$ collision data corresponding to an integrated luminosity of 6.32 fb$^{-1}$, collected by the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV. The absolute branching fraction for this decay is measured to be $mathcal{B}(D^+_s to pi^+ pi^+ pi^- eta) = (3.12pm0.13_{rm stat.}pm0.09_{rm syst.})$%. The first amplitude analysis of this decay reveals the sub-structures in $D^{+}_{s}rightarrow pi^{+}pi^{+}pi^{-}eta$ and determines the relative fractions and the phases among these sub-structures. The dominant intermediate process is $D^{+}_{s}rightarrow a_1(1260)^+ eta, a_1(1260)^+ rightarrow rho(770)^0pi^+$ with a branching fraction of $(1.73 pm 0.14_{rm stat.} pm 0.08_{rm syst.})$%. We also observe the W-annihilation process $D^{+}_{s}rightarrow a_0(980)^+rho(770)^0$, $a_0(980)^+ to pi^+ eta$ with a branching fraction of $(0.21pm0.08_{rm stat.}pm0.05_{rm syst.})$%, which is larger than the branching fractions of other measured pure W-annihilation decays by one order of magnitude.
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 $({5.7^{+2.5}_{-2.1}}_{rm stat}pm0.2_{rm syst})times10^{-5}$.
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.
Using 6.32 fb$^{-1}$ of $e^+e^-$ collision data collected by the BESIII detector at the center-of-mass energies between 4.178 and 4.226 GeV,~an amplitude analysis of the $D^{+}_{s}rightarrow K^{0}_{S}K^{-}pi^{+}pi^{+}$ decays is performed for the first time to determine the intermediate-resonant contributions. The dominant component is the $D_s^+ to K^*(892)^+overline{K}^*(892)^0$ decay with a fraction of $(40.6pm2.9_{rm stat}pm4.9_{rm sys})$%. Our results of the amplitude analysis are used to obtain a more precise measurement of the branching fraction of the $D^{+}_{s}rightarrow K^{0}_{S}K^{-}pi^{+}pi^{+}$ decay, which is determined to be $(1.46pm0.05_{rm stat}pm0.05_{rm sys}$)%.
The branching fractions of the doubly Cabibbo-suppressed decays $D^+rightarrow K^-K^+K^+$, $D^+rightarrow pi^-pi^+K^+$ and $D^+_srightarrowpi^-K^+K^+$ are measured using the decays $D^+rightarrow K^-pi^+pi^+$ and $D^+_srightarrow K^-K^+pi^+$ as normalisation channels. The measurements are performed using proton-proton collision data collected with the LHCb detector at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 2.0 fb$^{-1}$. The results are begin{align} frac {mathcal{B}(D^+rightarrow K^-K^+K^+)} {mathcal{B}(D^+rightarrow K^-pi^+pi^+)}& = (6.541 pm 0.025 pm 0.042) times 10^{-4}, onumber frac {mathcal{B}(D^+rightarrow pi^-pi^+K^+)} {mathcal{B}(D^+rightarrow K^-pi^+pi^+)}& = (5.231 pm 0.009 pm 0.023) times 10^{-3}, onumber frac {mathcal{B}(D^+_srightarrowpi^-K^+K^+)} {mathcal{B}(D^+_srightarrow K^-K^+pi^+)}& = (2.372 pm 0.024 pm 0.025) times 10^{-3}, onumber end{align} where the uncertainties are statistical and systematic, respectively. These are the most precise measurements up to date.
M. Ablikim
,M. N. Achasov
,S. Ahmed
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(2018)
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"Observation of the $W$-Annihilation Decay $D^{+}_{s} rightarrow omega pi^{+}$ and Evidence for $D^{+}_{s} rightarrow omega K^{+}$"
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Yu Lu
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