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Register a new userMeasurements of $psi(3686) to K^{-} Lambda bar{Xi}^{+} +c.c.$ and $psi(3686) to gamma K^{-} Lambda bar{Xi}^{+} +c.c$
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Using a sample of $1.06times10^8 psip$ events produced in $e^+e^-$ collisions at $sqrt{s}$ = 3.686 GeV and collected with the BESIII detector at the BEPCII collider, we present studies of the decays $klx+c.c.$ and $gklx+c.c.$. We observe two hyperons, $Xi(1690)^-$ and $Xi(1820)^-$, in the $K^-Lambda$ invariant mass distribution in the decay $klx+c.c.$ with significances of $4.9 sigma$ and $6.2 sigma$, respectively. The branching fractions of $klx+c.c.$, $ksx+c.c.$, $psiptogamma chi_{cJ}to gamma K^- Lambda bar{Xi}^+ +c.c.$ $(J=0, 1, 2)$, and $psipto Xi(1690/1820)^{-} bar{Xi}^++c.c$ with subsequent decay $Xi(1690/1820)^-to K^-Lambda$ are measured for the first time.
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Based on the data sample of $448.1times10^{6}$ $psi(3686)$ events collected with the BESIII detector at BEPCII, we present a study of the decays $psi(3686)rightarrowgammachi_{cJ}rightarrowgammabar{p}K^{*+}Lambda+c.c.$ and $psi(3686)rightarrowbar{p}K^{*+}Lambda+c.c.$. The branching fractions of $chi_{cJ}rightarrowbar{p}K^{*+}Lambda+c.c.$ ($J$=0, 1, 2) are measured to be $(4.8pm0.7pm0.5)times10^{-4}$, $(5.0pm0.5pm0.4)times10^{-4}$, and $(8.2pm0.9pm0.7)times10^{-4}$, respectively, where the first uncertainties are statistical and the second systematic. The branching fraction of $psi(3686)rightarrowbar{p}K^{*+}Lambda+c.c.$ is measured to be $(6.3pm0.5pm0.5)times10^{-5}$. All these decay modes are observed for the first time.
Based on $4.481times10^8$ $psi(3686)$ events collected with the BESIII detector at BEPCII, the branching fraction of the isospin violating decay $psi(3686)rightarrowbar{Sigma}^{0}Lambda+c.c.$ is measured to be $(1.60 pm 0.31 pm 0.13~pm~0.58) times 10^{-6}$, where the first uncertainty is statistical, the second is systematic, and the third is the uncertainty arising from interference with the continuum. This result is significantly smaller than the measurement based on CLEO-c data sets. The decays $chi_{cJ} rightarrowLambdabar{Lambda}$ are measured via $psi(3686)rightarrowgammachi_{cJ}$, and the branching fractions are determined to be $mathcal{B}left(chi_{c0}rightarrowLambdabar{Lambda}right)=(3.64 pm 0.10 pm 0.10 pm 0.07)times 10^{-4}$, $mathcal{B}left(chi_{c1}rightarrowLambdabar{Lambda}right)=(1.31pm0.06 pm 0.06 pm0.03)times 10^{-4}$, $mathcal{B}left(chi_{c2}rightarrowLambdabar{Lambda}right)=(1.91pm0.08 pm 0.17 pm0.04)times 10^{-4}$, where the third uncertainties are systematic due to the $psi(3686) rightarrow gamma chi_{c J}$ branching fractions.
Using $(448.1pm2.9)times 10^{6}$ $psi(3686)$ events collected with the BESIII detector and a single-baryon tagging technique, we present the first observation of the decays $psi(3686)toXi(1530)^{0}bar{Xi}(1530)^{0}$ and $Xi(1530)^{0}bar{Xi}^0$. The branching fractions are measured to be ${cal{B}}(psi(3686)toXi(1530)^{0}bar{Xi}(1530)^{0}) = (6.77pm0.14pm0.39)times10^{-5}$ and ${cal{B}}(psi(3686)toXi(1530)^{0}bar{Xi}^{0}) = (0.53pm0.04pm0.03)times10^{-5}$. Here, the first and second uncertainties are statistical and systematic, respectively. In addition, the parameter associated with the angular distribution for the decay $psi(3686)toXi(1530)^{0}bar{Xi}(1530)^0$ is determined to be $alpha = 0.32pm0.19pm0.07$, in agreement with theoretical predictions within one standard deviation.
We observe the decay $psi(3686) to n bar{n}$ for the first time and measure $psi(3686) to p bar{p}$ with improved accuracy by using $1.07times 10^8$ $psi(3686)$ events collected with the BESIII detector. The measured branching fractions are $mathcal{B}(psi(3686) to n bar{n}) = (3.06 pm 0.06 pm 0.14)times 10^{-4}$ and $mathcal{B}(psi(3686) to p bar{p}) = (3.05 pm 0.02 pm 0.12) times 10^{-4}$. Here, the first uncertainties are statistical and the second ones systematic. With the hypothesis that the polar angular distributions of the neutron and proton in the center-of-mass system obey $1+alpha cos^2theta$, we determine the $alpha$ parameters to be $alpha_{nbar{n}} = 0.68 pm 0.12 pm 0.11$ and $alpha_{pbar{p}} = 1.03 pm 0.06 pm 0.03$ for $psi(3686)to nbar{n}$ and $psi(3686)to pbar{p}$, respectively.
Using the data samples of $(1310.6pm7.2 )times 10^{6}$ $J/psi$ events and $(448.1pm2.9)times 10^{6}$ $psi(3686)$ events collected with the BESIII detector, we search for the rare decays $J/psi to D^{0} e^{+}e^{-} +c.c.$ and $psi(3686) to D^{0} e^{+}e^{-} +c.c.$. No significant signals are observed and the corresponding upper limits on the branching fractions at the $90%$ confidence level are determined to be $Br(J/psi to D^{0} e^{+}e^{-} +c.c.)< 8.5times 10^{-8}$ and $Br (psi(3686) to D^{0} e^{+}e^{-} +c.c.)<1.4times 10^{-7}$, respectively. Our limit on $Br(J/psi to D^{0} e^{+}e^{-} +c.c.)$ is more stringent by two orders of magnitude than the previous results, and the $Br(psi(3686) to D^{0} e^{+}e^{-} +c.c.)$ is measured for the first time.
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