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Register a new userAnalysis of the decay $D^0rightarrow K_{S}^{0} K^{+} K^{-}$
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Using a data sample of $2.93~fb^{-1}$ of $e^+e^-$ collisions collected at $sqrt{s}=3.773 GeV$ in the BESIII experiment, we perform an analysis of the decay $D^0rightarrow K_{S}^{0} K^{+} K^{-}$. The Dalitz plot is analyzed using $1856pm 45$ flavor-tagged signal decays. We find that the Dalitz plot is well described by a set of six resonances: $a_0(980)^0$, $a_0(980)^+$, $phi(1020)$, $a_2(1320)^+$, $a_2(1320)^-$ and $a_0(1450)^-$. Their magnitudes, phases and fit fractions are determined as well as the coupling of $a_0(980)$ to $Kbar{K}$, $g_{Kbar{K}}=3.77pm 0.24text{(stat.)}pm0.35text{(sys.)} GeV$. The branching fraction of the decay $D^0rightarrow K_{S}^{0} K^{+} K^{-}$ is measured using $11660pm 118$ untagged signal decays to be $(4.51pm 0.05text{(stat.)}pm 0.16text{(sys.)})10^{-3}$. Both measurements are limited by their systematic uncertainties.
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We measure the decay $B_s^0rightarrow K^0overline{K}^0$ using data collected at the $Upsilon(5S)$ resonance with the Belle detector at the KEKB $e^+e^-$ collider. The data sample used corresponds to an integrated luminosity of 121.4 ${rm fb^{-1}}$. We measure a branching fraction $mathcal{B}(B_s^0rightarrow K^0overline{K}^0) = [19.6,^{+5.8}_{-5.1}({rm stat.}),pm1.0({rm sys.}),pm 2.0(N^{}_{B_s^0overline{B}_s^0})]times 10^{-6}$ with a significance of 5.1 standard deviations. This measurement constitutes the first observation of this decay.
Using an $e^{+}e^{-}$ annihilation data sample corresponding to an integrated luminosity of $3.19~mathrm{fb}^{-1}$ and collected at a center-of-mass energy $sqrt{s} = 4.178~mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fractions $mathcal{B}(D_{s}^{+} rightarrow K_{S}^{0}K^{+}) = (1.425pm0.038_{rm stat.}pm0.031_{rm syst.})%$ and $mathcal{B}(D_{s}^{+} rightarrow K_{L}^{0}K^{+}) =(1.485pm0.039_{rm stat.}pm0.046_{rm syst.})%$. The branching fraction of $D_{s}^{+} rightarrow K_{S}^{0}K^{+}$ is compatible with the world average and that of $D_{s}^{+} rightarrow K_{L}^{0}K^{+}$ is measured for the first time. We present the first measurement of the $K_{S}^{0}$-$K_{L}^{0}$ asymmetry in the decays $D_{s}^{+} rightarrow K_{S,L}^{0}K^{+}$, and $R(D_{s}^{+} rightarrow K_{S,L}^{0}K^{+})=frac{mathcal{B}(D_{s}^{+} rightarrow K_{S}^{0}K^{+}) -mathcal{B}(D_{s}^{+} rightarrow K_{L}^{0}K^{+})}{mathcal{B}(D_{s}^{+} rightarrow K_{S}^{0}K^{+}) +mathcal{B}(D_{s}^{+} rightarrow K_{L}^{0}K^{+})}= (-2.1pm1.9_{rm stat.}pm1.6_{rm syst.})%$. In addition, we measure the direct $CP$ asymmetries $A_{rm CP}(D_{s}^{pm} rightarrow K_{S}^{0}K^{pm}) = (0.6pm2.8_{rm stat.}pm0.6_{rm syst.})%$ and $A_{rm CP}(D_{s}^{pm} rightarrow K_{L}^{0}K^{pm}) = (-1.1pm2.6_{rm stat.}pm0.6_{rm syst.})%$.
A search for $B_{(s)}^{0} to K_{S}^{0} K^{*}(892)^{0}$ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of $1.0~text{fb}^{-1}$, collected with the LHCb detector at a centre-of-mass energy of $7~text{TeV}$. The $B_{s}^{0} to K_{S}^{0} K^{*}(892)^{0}$ decay is observed for the first time, with a significance of 7.1 standard deviations. The branching fraction is measured to be begin{equation*} mathcal{B}(B_{s}^{0} to bar{K}^{0} K^{*}(892)^{0}) + mathcal{B}(B_{s}^{0} to K^{0} bar{K}^{*}(892)^{0}) = (16.4 pm 3.4 pm 2.3) times 10^{-6}, end{equation*} where the first uncertainty is statistical and the second is systematic. No evidence is found for the decay $B^{0} to K_{S}^{0} K^{*}(892)^{0}$ and an upper limit is set on the branching fraction, $mathcal{B}(B^{0} to bar{K}^{0} K^{*}(892)^{0}) + mathcal{B}(B^{0} to K^{0} bar{K}^{*}(892)^{0}) < 0.96 times 10^{-6}, $ at $90,% $ confidence level. All results are consistent with Standard Model predictions.
A binned Dalitz plot analysis of the decays $B^0 to D K^{ast 0}$, with $D to K_{S}^{0} pi^{+} pi^{-}$ and $K_{S}^{0} K^{+} K^{-}$, is performed to measure the observables $x_pm$ and $y_pm$, which are related to the CKM angle $gamma$ and the hadronic parameters of the decays. The $D$ decay strong phase variation over the Dalitz plot is taken from measurements performed at the CLEO-c experiment, making the analysis independent of the $D$ decay model. With a sample of proton-proton collision data, corresponding to an integrated luminosity of $3.0,rm{fb}^{-1}$, collected by the LHCb experiment, the values of the $CP$ violation parameters are found to be $x_+ = 0.05 pm 0.35 pm 0.02$, $x_-=-0.31pm 0.20 pm 0.04$, $y_+=-0.81pm 0.28pm 0.06$ and $y_-=0.31pm 0.21 pm 0.05$, where the first uncertainties are statistical and the second systematic. These observables correspond to values $gamma$ = $(71 pm 20)^circ$, $r_{B^0} = 0.56pm 0.17$ and $delta_{B^0} = (204,^{+21}_{-20})^circ$. The parameters $r_{B^0}$ and $delta_{B^0}$ are the magnitude ratio and strong phase difference between the suppressed and favoured $B^0$ decay amplitudes, and have been measured in a region of $pm 50$ MeV/$c^2$ around the $K^{ast}(892)^{0}$ mass and with the magnitude of the cosine of the $K^{ast}(892)^{0}$ helicity angle larger than 0.4.
Decays of the form $B^{0}_{(s)}rightarrow J/psi K_{{rm S}}^{0} h^+ h^{left(primeright) -}$ ($h^{(prime)} = K, pi$) are searched for in proton-proton collision data corresponding to an integrated luminosity of $1.0 , {rm fb}^{-1}$ recorded with the LHCb detector. The first observation of the $B^{0}_{s}rightarrow J/psi K_{{rm S}}^{0} K^{pm} pi^{mp}$ decay is reported, with significance in excess of 10 standard deviations. The $B^{0}rightarrow J/psi K_{{rm S}}^{0} K^{+} K^{-}$ decay is also observed for the first time. The branching fraction of $B^{0}rightarrow J/psi K_{{rm S}}^{0} pi^{+} pi^{-}$ is determined, to significantly better precision than previous measurements, using $B^0 rightarrow J/psi K_{{rm S}}^{0}$ as a normalisation channel. Branching fractions and upper limits of the other $B^{0}_{(s)}rightarrow J/psi K_{{rm S}}^{0} h^+ h^{left(primeright) -}$ modes are determined relative to that of the $B^{0}rightarrow J/psi K_{{rm S}}^{0} pi^{+} pi^{-}$ decay.
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