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تسجيل مستخدم جديدSearch for $eta$ and $eta$ Invisible Decays in $J/psitophieta$ and $phieta$
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Using a sample of $(225.3pm 2.8)times 10^{6}$ $J/psi$ decays collected with the BESIII detector at BEPCII, searches for invisible decays of $eta$ and $eta^prime$ in $J/psitophieta$ and $phieta^prime$ are performed. Decays of $phi to K^{+}K^{-}$ are used to tag the $eta$ and $eta^prime$ decays. No signals above background are found for the invisible decays, and upper limits at the 90% confidence level are determined to be $2.58times10^{-4}$ for the ratio $frac{mathcal{B}(etatorm{invisible})}{mathcal{B}(etatogammagamma)}$ and $2.39times10^{-2}$ for $frac{mathcal{B}(eta^primetorm{invisible})}{mathcal{B}(eta^prime togammagamma)}$.
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Using a sample of 225.3 million $jpsi$ events collected with the BESIII detector at the BEPCII $e^+e^-$ collider in 2009, searches for the decays of $eta$ and $eta^primetopi^+ e^- bar{ u}_e +c.c.$ in $jpsi to phi eta$ and $phieta^prime$ are performed
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We report an observation of the $B^{pm} to J/psi eta K^{pm}$ and $B^0 to J/psi eta K^0_S$ decays using 772$times 10^{6}$ $Bbar{B}$ pairs collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.
We obtain the branching fractions ${cal B}(B^{pm}rightarrow J/psieta K^{pm})=(1.27pm 0.11{rm (stat.)pm 0.11{rm (syst.)})}times10^{-4}$ and ${cal B}(B^0to J/psi eta K^0_S)=(5.22 pm 0.78 {rm(stat.)} pm 0.49{rm(syst.)})times10^{-5}$. We search for a new narrow charmonium(-like) state $X$ in the $J/psi eta$ mass spectrum and find no significant excess. We set upper limits on the product of branching fractions, ${cal B}(B^pm to XK^pm){cal B}(X to J/psi eta)$, at 3872 MeV$/c^2$ where a $C$-odd partner of X(3872) may exist, at $psi(4040)$ and $psi(4160)$ assuming their known mass and width, and over a range from 3.8 to 4.8 GeV$/c^2$. % at a 5 MeV$/c^2$ step. The obtained upper limits at 90% confidence level for $X^{C{rm -odd}}(3872)$, $psi(4040)$ and $psi(4160)$ are 3.8$times 10^{-6}$, 15.5$times 10^{-6}$ and 7.4$times 10^{-6}$, respectively.
In this work, we calculate the branching ratios for the $eta(eta)rightarrowbar{ell}ell$ decays, where $ell = e,mu$. These processes have tiny rates in the standard model due to spin flip, loop, and electromagnetic suppression, for what they could be
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We present the first search for the rare decay of $eta^prime$ into $K^{pm}pi^{mp}$ in $J/psitophieta^{prime}$, using a sample of $1.3times10^{9}$ $J/psi$ events collected with the BESIII detector. No significant signal is observed, and the upper limi
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