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Register a new userBranching fraction measurements of chi_{c0} and chi_{c2} to pi^0pi^0 and etaeta
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The BESIII Collaboration
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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.
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Using a sample of 106 million $psi(3686)$ decays, the branching fractions of $psi(3686) to gamma chi_{c0}, psi(3686) to gamma chi_{c1}$, and $psi(3686) to gamma chi_{c2}$ are measured with improved precision to be $(9.389 pm 0.014 pm 0.332),%$, $(9.905 pm 0.011 pm 0.353),% $, and $(9.621 pm 0.013 pm 0.272),% $, respectively, where the first uncertainties are statistical and the second ones are systematic. The product branching fractions of $psi(3686) to gamma chi_{c1}, chi_{c1} to gamma J/psi$ and $psi(3686) to gamma chi_{c2}, chi_{c2} to gamma J/psi$ and the branching fractions of $chi_{c1} to gamma J/psi$ and $chi_{c2} to gamma J/psi$ are also presented.
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.
Based on a data sample of 106 M $psi^{prime}$ events collected with the BESIII detector, the decays $psi^{prime}argammachi_{c0, 2}$,$chi_{c0, 2}argammagamma$ are studied to determine the two-photon widths of the $chi_{c0, 2}$ states. The two-photon decay branching fractions are determined to be ${cal B}(chi_{c0}argammagamma) = (2.24pm 0.19pm 0.12pm 0.08)times 10^{-4}$ and ${cal B}(chi_{c2}argammagamma) = (3.21pm 0.18pm 0.17pm 0.13)times 10^{-4}$. From these, the two-photon widths are determined to be $Gamma_{gamma gamma}(chi_{c0}) = (2.33pm0.20pm0.13pm0.17)$ keV, $Gamma_{gamma gamma}(chi_{c2}) = (0.63pm0.04pm0.04pm0.04)$ keV, and $cal R$ $=Gamma_{gamma gamma}(chi_{c2})/Gamma_{gamma gamma}(chi_{c0})=0.271pm 0.029pm 0.013pm 0.027$, where the uncertainties are statistical, systematic, and those from the PDG ${cal B}(psi^{prime}argammachi_{c0,2})$ and $Gamma(chi_{c0,2})$ errors, respectively. The ratio of the two-photon widths for helicity $lambda=0$ and helicity $lambda=2$ components in the decay $chi_{c2}argammagamma$ is measured for the first time to be $f_{0/2} =Gamma^{lambda=0}_{gammagamma}(chi_{c2})/Gamma^{lambda=2}_{gammagamma}(chi_{c2}) = 0.00pm0.02pm0.02$.
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.
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.
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