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Register a new userSearch for vector charmonium(-like) states in the $e^+e^- rightarrow eta J/psi$ line shape
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The cross section of $e^+e^- rightarrow eta J/psi$ has been measured by BESIII and Belle experiments. Fit to the $e^+e^- rightarrow eta J/psi$ line shape, three resonant structures are evident. The parameters for the three resonant structures are $M_{1}=(3980pm17pm7)$ MeV/$c^{2}$, $Gamma_{1}=(104pm32pm13)$ MeV; $M_{2}=(4219pm5pm4)$ MeV/$c^{2}$, $Gamma_{2}=(63pm9pm3)$ MeV; $M_{3}=(4401pm12pm4)$ MeV/$c^{2}$, $Gamma_{3}=(49pm19pm4)$ MeV, where the first uncertainties are statistical and the second systematic. We attribute the three structures to $psi(4040)$, $Y(4220)$ and $psi(4415)$ states. The branching fractions $mathcal{B}(psi(4040) rightarrow eta J/psi)$ and $mathcal{B}(psi(4415) rightarrow eta J/psi)$ are given. If $Y(4220)$ is taken as $psi(4S)$ state, the branching fraction $mathcal{B}(psi(4S) rightarrow eta J/psi)$ is also given. Combining all $Y(4220)$ parameters obtained from different decays, we give average parameters for $Y(4220)$, which are $M_{Y(4220)}=(4220.8pm2.4)$ MeV/$c^{2}$, $Gamma_{Y(4220)}=(54.8pm3.3)$ MeV.
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The cross sections of $e^+e^- rightarrow omegachi_{cJ(J=0,1,2)}$ have been measured by BESIII. We try to search for vector charmonium(-like) states $Y(4220)$, $Y(4360)$, $psi(4415)$ and $Y(4660)$ in the $e^+e^- rightarrow omegachi_{cJ(J=0,1,2)}$ line shapes. The $omegachi_{c0}$ mainly comes from $Y(4220)$, $omegachi_{c1}$ mainly comes from $Y(4660)$ and $omegachi_{c2}$ mainly comes from $psi(4415)$, maybe partly comes from $Y(4360)$ or $Y(4660)$. For the charmonium(-like) states that are not significant in the $e^+e^- rightarrow omegachi_{cJ(J=0,1,2)}$ line shape, we also give the $90%$ confidence level upper limits on the electron partial width multiplied by branching fraction. These results are helpful to study the nature of charmonium(-like) states in this energy region.
Using $4.479 times 10^{8}$ $psi(3686)$ events collected with the BESIII detector, we search for the decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}$ and $chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi$. The decays $psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}$ and $chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi$ are observed for the first time. The measured branching fractions are $mathcal{B}(psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2}) = (11.7 pm 2.5 pm 1.0)times10^{-4}$, $(8.6 pm 0.3 pm 0.6)times10^{-4}$, $(6.9 pm 0.5 pm 0.6)times10^{-4}$, and $mathcal{B}(chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi) = (1.51 pm 0.30 pm 0.13)times10^{-4}$, $(3.73 pm 0.09 pm 0.25)times10^{-3}$, $(2.48 pm 0.08 pm 0.16)times10^{-3}$. The ratios of the branching fractions $frac{mathcal{B}(psi(3686) rightarrow e^{+}e^{-}chi_{c0,1,2})}{mathcal{B}(psi(3686) rightarrow gammachi_{c0,1,2})}$ and $frac{mathcal{B}(chi_{c0,1,2} rightarrow e^{+}e^{-}J/psi)}{mathcal{B}(chi_{c0,1,2} rightarrow gamma J/psi)}$ are also reported.
We study the possibility of the scalar charmonium and glueball mixing in $e^+ e^-$ annihilation at $sqrt{s}=10.6$ GeV. The effects can be used to explain the unexpected large cross section ($12pm 4$ fb) and the anomalous angular distribution ($alpha= -1.1^{+0.8}_{-0.6}$) of the exclusive $e^+e^-to J/psichi_{c0}$ process observed by Belle experiments at KEKB. We calculate the helicity amplitudes for the process $e^+ e^- to J/psi H(0^{++})$ in NRQCD, where $H(0^{++})$ is the mixed state. We present a detailed analysis on the total cross section and various angular asymmetries which could be useful to reveal the existence of the scalar glueball state.
We study the electromagnetic Dalitz decay $J/psi to e^+e^- eta$ and search for di-electron decays of a dark gauge boson ($gamma$) in $J/psi to gamma eta$ with the two $eta$ decay modes $eta rightarrow gamma gamma$ and $eta rightarrow pi^+pi^-pi^0$ using $(1310.6pm 7.0)times10^6$ $J/psi$ events collected with the BESIII detector. The branching fraction of $J/psi to e^+e^- eta$ is measured to be $(1.43 pm 0.04 ({rm stat}) pm 0.06 ({rm syst}))times 10^{-5}$, with a precision that is improved by a factor of $1.5$ over the previous BESIII measurement. The corresponding di-electron invariant mass dependent modulus square of the transition form factor is explored for the first time, and the pole mass is determined to be $Lambda = 2.84 pm 0.11({rm stat}) pm 0.08({rm syst})$ GeV/$c^2$. We find no evidence of $gamma$ production and set $90%$ confidence level upper limits on the product branching fraction $mathcal{B}(J/psi to gamma eta)times mathcal{B}(gamma to e^+e^-)$ as well as the kinetic mixing strength between the Standard Model photon and $gamma$ in the mass range of $0.01 le m_{gamma} le 2.4$ GeV/$c^2$.
Using a data sample of $448.1times10^6$ $psi(3686)$ events collected at $sqrt{s}=$ 3.686 GeV with the BESIII detector at the BEPCII, we search for the rare decay $J/psi to phi e^+ e^-$ via $psi(3686) to pi^+pi^- J/psi $. No signal events are observed and the upper limit on the branching fraction is set to be $mathcal{B}(J/psi to phi e^+ e^-) < 1.2 times 10^{-7}$ at the 90% confidence level, which is still about one order of magnitude higher than the Standard Model prediction.
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