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Register a new userObservation of $chi_{c2}toetaeta$ and $chi_{c0,2}toetaeta$
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Using a sample of $447.9times 10^6$ $psi(3686)$ events collected with the BESIII detector in 2009 and 2012, we study the decays $chi_{c0,2}to$ $etaeta$ and $etaeta$. The decays $chi_{c2}toetaeta$, $chi_{c0}toetaeta$ and $chi_{c2}toetaeta$ are observed for the first time with statistical significances of $9.6sigma$, $13.4sigma$ and $7.5sigma$, respectively. The branching fractions are determined to be $mathcal{B}(chi_{c0}toetaeta) =(2.19pm0.03pm0.14)times10^{-3}$, $mathcal{B}(chi_{c2}toetaeta) = (4.76pm0.56pm0.38)times10^{-5}$, $mathcal{B}(chi_{c0}toetaeta) = (8.92pm0.84pm0.65)times10^{-5}$ and $mathcal{B}(chi_{c2}toetaeta) = (2.27pm0.43pm0.25)times10^{-5}$, where the first uncertainties are statistical and the second systematic. The precision for the measurement of $mathcal{B}(chi_{c0}toetaeta)$ is significantly improved compared to previous measurements. Based on the measured branching fractions, the role played by the doubly and singly Okubo-Zweig-Iizuka disconnected transition amplitudes for $chi_{c0,2}$ decays into pseudoscalar meson pairs can be clarified.
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The decays $chi_{c1} rightarrow J/psi mu^+ mu^-$ and $chi_{c2} rightarrow J/psi mu^+ mu^-$ are observed and used to study the resonance parameters of the $chi_{c1}$ and $chi_{c2}$ mesons. The masses of these states are measured to be m(chi_{c1}) = 3510.71 pm 0.04(stat) pm 0.09(syst)MeV,, m(chi_{c2}) = 3556.10 pm 0.06(stat) pm 0.11(syst)MeV,, where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. The momentum-scale uncertainties largely cancel in the mass difference m(chi_{c2}) - m(chi_{c1}) = 45.39 pm 0.07(stat) pm 0.03(syst)MeV,. The natural width of the $chi_{c2}$ meson is measured to be $$Gamma(chi_{c2}) = 2.10 pm 0.20(stat) pm 0.02(syst)MeV,.$$ These results are in good agreement with and have comparable precision to the current world averages.
The first observation of the decays $Lambda_b^0 to chi_{c1} p K^-$ and $Lambda_b^0 to chi_{c2} p K^-$ is reported using a data sample corresponding to an integrated luminosity of $3.0$ fb$^{-1}$, collected by the LHCb experiment in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV. The following ratios of branching fractions are measured begin{eqnarray*} frac{{cal B}(Lambda_b^0 to chi_{c1} p K^-)}{{cal B}(Lambda_b^0 to J/psi p K^-)} = 0.242 pm 0.014 pm 0.013 pm 0.009, frac{{cal B}(Lambda_b^0 to chi_{c2} p K^-)}{{cal B}(Lambda_b^0 to J/psi p K^-)} = 0.248 pm 0.020 pm 0.014 pm 0.009, frac{{cal B}(Lambda_b^0 to chi_{c2} p K^-)}{{cal B}(Lambda_b^0 to chi_{c1} p K^-)} = 1.02 pm 0.10 pm 0.02 pm 0.05, end{eqnarray*} where the first uncertainty is statistical, the second systematic and the third due to the uncertainty on the branching fractions of the $chi_{c1}to J/psigamma$ and $chi_{c2} to J/psigamma$ decays. Using both decay modes, the mass of the $Lambda_b^0$ baryon is also measured to be $m_{Lambda_b^0} = 5619.44 pm 0.28 pm 0.26$ MeV/$c^2$, where the first and second uncertainties are statistical and systematic, respectively.
Using a sample of 1.06 times 10^8 psi^{prime} decays collected by the BESIII detector, chi_{c0} and chi_{c2} decays into pi^0pi^0 and etaeta are studied. The branching fraction results are Br(chi_{c0}topi^0pi^0)=(3.23pm 0.03pm0.23 pm 0.14)times 10^{-3}, Br(chi_{c2}topi^0pi^0)=(8.8pm 0.2pm 0.6pm0.4)times 10^{-4}, Br(chi_{c0}toetaeta)=(3.44pm 0.10pm0.24 pm0.2)times 10^{-3}, and Br(chi_{c2}toetaeta)=(6.5pm 0.4pm 0.5pm 0.3)times 10^{-4}, where the uncertainties are statistical, systematic due to this measurement, and systematic due to the branching fractions of psi^{prime}togammachi_{cJ}, respectively. The results provide information on the decay mechanism of chi_c states into pseudoscalars.
We report inclusive and exclusive measurements for $chi_{c1}$ and $chi_{c2}$ production in $B$ decays. We measure $mathcal{B}(B to chi_{c1} X)$= $(3.03 pm 0.05(mbox{stat}) pm 0.24(mbox{syst})) times 10^{-3}$ and $mathcal{B}(B to chi_{c2} X)$= $(0.70 pm 0.06(mbox{stat}) pm 0.10(mbox{syst})) times 10^{-3}$. For the first time, $chi_{c2}$ production in exclusive $B$ decays in the modes $B^0 to chi_{c2}pi^- K^+$ and $B^+ to chi_{c2} pi^+ pi^- K^+$ has been observed, along with first evidence for the $B^+ to chi_{c2} pi^+ K_S^0$ decay mode. For $chi_{c1}$ production, we report the first observation in the $B^+ to chi_{c1} pi^+ pi^- K^+$, $B^0 to chi_{c1} pi^+ pi^- K_S^0$ and $B^0 to chi_{c1} pi^0 pi^- K^+$ decay modes. Using these decay modes, we observe a difference in the production mechanism of $chi_{c2}$ in comparison to $chi_{c1}$ in $B$ decays. In addition, we report searches for $X(3872)$ and $chi_{c1}(2P)$ in the $B^+ to (chi_{c1} pi^+ pi^-) K^+$ decay mode. The reported results use $772 times 10^{6}$ $Boverline{B}$ events collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider.
Prompt production of charmonium $chi_{c0}$, $chi_{c1}$ and $chi_{c2}$ mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of $sqrt{s}=7$TeV. The $chi_{c}$ mesons are identified through their decay to $J/psigamma$, with $J/psitomu^+mu^-$ using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of $1.0mathrm{fb}^{-1}$ collected by the LHCb detector, is used to measure the relative prompt production rate of $chi_{c1}$ and $chi_{c2}$ in the rapidity range $2.0<y<4.5$ as a function of the $J/psi$ transverse momentum from 3 to 20 GeV$/c$. First evidence for $chi_{c0}$ meson production at a high-energy hadron collider is also presented.
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