اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدImproved measurements of two-photon widths of the $chi_{cJ}$ states and helicity analysis for $chi_{c2}togammagamma$
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Based on $448.1 times 10^6$ $psi(3686)$ events collected with the BESIII detector, the decays $psi(3686)togammachi_{cJ}, chi_{cJ} to gammagamma~(J=0, 1, 2)$ are studied. The decay branching fractions of $chi_{c0,c2} to gammagamma$ are measured to be $mathcal{B}(chi_{c0}togammagamma) = (1.93 pm 0.08 pm 0.05 pm 0.05)times 10^{-4}$ and $mathcal{B}(chi_{c2}togammagamma) = (3.10 pm 0.09 pm 0.07 pm 0.11)times 10^{-4} $, which correspond to two-photon decay widths of $Gamma_{gammagamma}(chi_{c0}) = 2.03 pm 0.08 pm 0.06 pm 0.13 ~rm{keV}$ and $Gamma_{gammagamma}(chi_{c2}) = 0.60 pm 0.02 pm 0.01 pm 0.04 ~rm{keV}$ with a ratio of $mathcal{R}=Gamma_{gammagamma}(chi_{c2})/Gamma_{gammagamma}(chi_{c0})= 0.295 pm 0.014 pm 0.007 pm 0.027$, where the uncertainties are statistical, systematic and associated with the uncertainties of $mathcal{B}(psi(3686)togammachi_{c0,c2})$ and the total widths $Gamma(chi_{c0,c2})$, respectively. For the forbidden decay of $chi_{c1}togammagamma$, no signal is observed, and an upper limit on the two-photon width is obtained to be $Gamma_{gammagamma}(chi_{c1})<5.3 ~rm{eV}$ at the 90% confidence level. The ratio of the two-photon widths between helicity-zero and helicity-two components in the decay $chi_{c2}togammagamma$ is also measured to be $f_{0/2} = Gamma^{lambda=0}_{gammagamma}(chi_{c2})/Gamma^{lambda=2}_{gammagamma}(chi_{c2}) = (0.0 pm 0.6 pm 1.2)times 10^{-2}$, where the uncertainties are statistical and systematic, respectively.
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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 d
ecay 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 $f_{0/2} =Gamma^{lambda=0}_{gammagamma}(chi_{c2})/Gamma^{lambda=2}_{gammagamma}(chi_{c2}) = 0.00pm0.02pm0.02$.
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 observe
d 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.
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}) = 35
10.71 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.
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.
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