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Register a new userSearch for the reaction channel $e^+e^- rightarrow eta_ceta pi^+pi^-$ at center-of-mass energies from 4.23 to 4.60 GeV
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Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider, we search for the process $e^+e^-rightarrow eta_ceta pi^+pi^-$. The search is performed using five large data sets recorded at center-of-mass energies of 4.23, 4.26, 4.36, 4.42, and 4.60 GeV. The $eta_c$ meson is reconstructed in 16 exclusive decay modes. No signal is observed in the $eta_c$ mass region at any center-of-mass energy. The upper limits on the reaction cross sections are determined to be 6.2, 10.8, 27.6, 22.6 and 23.7 pb at the 90% confidence level at the center-of-mass energies listed above.
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We report a study of the $e^{+}e^{-} to D^{+} D^{-} pi^{+} pi^{-}$ process using $e^{+}e^{-}$ collision data samples with an integrated luminosity of $2.5,rm{fb}^{-1}$ at center-of-mass energies from 4.36 to $4.60 rm{GeV}$, collected with the BESIII detector at the BEPCII storage ring. The $D_{1}(2420)^+$ is observed in the $D^{+} pi^{+} pi^{-}$ mass spectrum. The mass and width of the $D_{1}(2420)^+$ are measured to be $(2427.2pm 1.0_{rm stat.}pm 1.2_{rm syst.}) rm{MeV}/c^2$ and $(23.2pm 2.3_{rm stat.} pm2.3_{rm syst.}) rm{MeV}$, respectively. The first errors are statistical and the second ones are systematic. In addition, the Born cross sections of the $e^{+}e^{-} to D_{1}(2420)^+D^- + c.c. to D^{+} D^{-} pi^{+} pi^{-}$ and $e^{+}e^{-} to psi(3770) pi^{+} pi^{-} to D^{+} D^{-} pi^{+} pi^{-}$ processes are measured as a function of the center-of-mass energy.
The cross section for the process $e^+e^-to pi^+pi^-J/psi$ is measured precisely at center-of-mass energies from 3.77 to 4.60~GeV using 9~fb$^{-1}$ of data collected with the BESIII detector operating at the BEPCII storage ring. Two resonant structures are observed in a fit to the cross section. The first resonance has a mass of $(4222.0pm 3.1pm 1.4)$~MeV/$c^2$ and a width of $(44.1pm 4.3pm 2.0)$~MeV, while the second one has a mass of $(4320.0pm 10.4 pm 7.0)$~MeV/$c^2$ and a width of $(101.4^{+25.3}_{-19.7}pm 10.2)$~MeV, where the first errors are statistical and second ones are systematic. The first resonance agrees with the $Y(4260)$ resonance reported by previous experiments. The precision of its resonant parameters is improved significantly. The second resonance is observed in $e^+e^-to pi^+pi^-J/psi$ for the first time. The statistical significance of this resonance is estimated to be larger than $7.6sigma$. The mass and width of the second resonance agree with the $Y(4360)$ resonance reported by the $BABAR$ and Belle experiments within errors. Finally, the $Y(4008)$ resonance previously observed by the Belle experiment is not confirmed in the description of the BESIII data.
We search for the process $e^{+}e^{-}rightarrow pi ^{+}pi ^{-} chi_{cJ}$ ($J=0,1,2$) and for a charged charmonium-like state in the $pi ^{pm} chi_{cJ}$ subsystem. The search uses data sets collected with the BESIII detector at the BEPCII storage ring at center-of-mass energies between 4.18 GeV and 4.60 GeV. No significant $pi ^{+}pi ^{-} chi_{cJ}$ signals are observed at any center-of-mass energy, and thus upper limits are provided which also serve as limits for a possible charmonium-like structure in the invariant $pi ^{pm} chi_{cJ}$ mass.
We present first evidence for the process $e^+e^-to gammaeta_c(1S)$ at six center-of-mass energies between 4.01 and 4.60~GeV using data collected by the BESIII experiment operating at BEPCII. These data sets correspond to a total integrated luminosity of 4.6~fb$^{-1}$. We measure the Born cross section at each energy using a combination of twelve $eta_c(1S)$ decay channels. Because the significance of the signal is marginal at each energy ($le3.0sigma$), we also combine all six energies under various assumptions for the energy-dependence of the cross section. If the process is assumed to proceed via the $Y(4260)$, we measure a peak Born cross section $sigma_{mathrm{ peak}}(e^+e^-togammaeta_c(1S)) = 2.11 pm 0.49 (mathrm{stat.}) pm 0.36 (mathrm{syst.})$~pb with a statistical significance of 4.2$sigma$.
Using $5.2 mathrm{fb}^{-1}$ $e^+ e^-$ annihilation data samples collected with the BESIII detector, we measure the cross sections of $e^+e^- to K_S^0 K^pm pi^mp pi^0$ and $K_{S}^{0}K^{pm}pi^{mp}eta$ at center-of-mass energies from $3.90$ to $4.60$ GeV. In addition, we search for the charmonium-like resonance $Y(4260)$ decays into $K_{S}^{0}K^{pm}pi^{mp}pi^0$ and $K_{S}^{0}K^{pm}pi^{mp}eta$, and $Z_c^{0,pm}(3900)$ decays into $K_{S}^{0}K^{pm}pi^{mp,0}$ and $K_{S}^{0}K^{pm}eta$. Corresponding upper limits are provided since no clear signal is observed.
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