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Register a new userObservation of the decay $psi(3686)$ $rightarrow$ $LambdabarSigma^{pm}pi^{mp}+c.c.$
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Using a sample of $1.06times10^{8}$ $psi(3686)$ events collected with the BESIII detector, we present the first observation of the decays of $psi(3686)$ $rightarrow$ $LambdabarSigma^{+}pi^{-}+c.c.$ and $psi(3686)$ $rightarrow$ $LambdabarSigma^{-}pi^{+}+c.c.$. The branching fractions are measured to be $mathcal{B}(psi(3686) rightarrow LambdabarSigma^{+}pi^{-} + c.c.)=(1.40pm 0.03 pm 0.13)times10^{-4}$ and $mathcal{B}(psi(3686) rightarrow LambdabarSigma^{-}pi^{+}+c.c.)=(1.54pm 0.04 pm 0.13)times10^{-4}$, where the first errors are statistical and the second ones systematic.
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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.
We study the process $e^{+}e^{-} rightarrow pi^{+}pi^{-}psi(3686)$ using 5.1 $fb^{-1}$ of data collected at 16 center-of-mass energy ($sqrt{s}$) points from 4.008 to 4.600$sim$GeV by the BESIII detector operating at the BEPCII collider. The measured Born cross sections for $e^{+}e^{-}rightarrow pi^{+}pi^{-}psi(3686)$ are consistent with previous results, but with much improved precision. A fit to the cross section shows contributions from two structures: the first has $M=4209.5pm7.4pm1.4$$sim$MeV/$c^{2}$ and $Gamma=80.1pm24.6pm2.9$$sim$MeV, and the second has $M=4383.8pm4.2pm0.8$$sim$MeV/c$^{2}$ and $Gamma=84.2pm12.5pm2.1$$sim$MeV, where the first errors are statistical and the second systematic. The lower-mass resonance is observed in the process $e^{+}e^{-}rightarrow pi^{+}pi^{-}psi(3686)$ for the first time with a statistical significance of $5.8sigma$. A charged charmonium-like structure is observed in the $pi^{pm}psi(3686)$ invariant mass spectrum for data at $sqrt{s} = 4.416~$GeV. A fit with an $S$-wave Breit-Wigner function yields a mass $M=4032.1pm2.4$~$MeV$^{2}$, where the errors are statistical only. However, there are still unresolved discrepancies between the fit model and data. The width of the intermediate state varies in a wide range for different kinematic regions within the data set. Therefore no simple interpretation of the data has been found, and a future data sample with larger statistics and more theoretical input will be required to better understand this issue.
A search for the $B^0_s !rightarrow D^{*pm} D^mp$ decay is performed using proton-proton collision data at centre-of-mass energies of $7$, $8$ and $13,text{TeV}$ collected by the LHCb experiment, corresponding to an integrated luminosity of $9,text{fb}^{-1}$. The decay is observed with a high significance and its branching fraction relative to the $B^0 !rightarrow D^{*pm} D^mp$ decay is measured to be begin{align*} frac{mathcal{B}(B_s^0 rightarrow D^{ast pm} D^{mp}) }{mathcal{B}(B^0 rightarrow D^{ast pm} D^{mp}) } = 0.137 pm 0.017 pm 0.002 pm 0.006 ,, end{align*} where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the $B_s^0$ and $B^0$ hadronisation fractions.
We search for the M1 radiative transition psi(3686) to gammaeta_{c}(2S) by reconstructing the exclusive eta_{c}(2S) to K_{S}^{0}K^{pm}pi^{mp}pi^{+}pi^{-} decay using 1.06 times 10^8 psi(3686) events collected with the BESIII detector. The signal is observed with a statistical significance of greater than 4 standard deviations. The measured mass of the eta_{c}(2S) is 3646.9 pm 1.6(stat) pm 3.6(syst) MeV/c^2, and the width is 9.9 pm 4.8(stat) pm 2.9(syst) MeV/c^2. The product branching fraction is measured to be B(psi(3686) to gammaeta_{c}(2S)) times B(eta_{c}(2S) to K_{S}^{0}K^{pm}pi^{mp}pi^{+}pi^{-}) = (7.03 pm 2.10(stat) pm 0.70(syst)) times 10^{-6}. This measurement complements a previous BESIII measurement of psi(3686) to gammaeta_{c}(2S) with eta_{c}(2S) to K_{S}^{0} K^{pm}pi^{mp} and K^{+}K^{-}pi^{0}.
The decay $B_crightarrow J/psi K^+ K^- pi^+$ is observed for the first time, using proton-proton collisions collected with the LHCb detector corresponding to an integrated luminosity of 3fb$^{-1}$. A signal yield of $78pm14$ decays is reported with a significance of 6.2 standard deviations. The ratio of the branching fraction of $B_c rightarrow J/psi K^+ K^- pi^+$ decays to that of $B_c rightarrow J/psi pi^+$ decays is measured to be $0.53pm 0.10pm0.05$, where the first uncertainty is statistical and the second is systematic.
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