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Register a new userPrecise measurement of the $e^+e^-to pi^+pi^-J/psi$ cross section at center-of-mass energies from 3.77 to 4.60 GeV
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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.
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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.
Using data samples collected with the BESIII detector operating at the BEPCII collider at center-of-mass energies from 3.810 to 4.600 GeV, we perform a study of $e^{+}e^{-} to eta J/psi$ and $pi^0 J/psi$. Statistically significant signals of $e^{+}e^{-} to eta J/psi$ are observed at $sqrt{s}$ = 4.190, 4.210, 4.220, 4.230, 4.245, 4.260, 4.360 and 4.420 GeV, while no signals of $e^{+}e^{-} to pi^{0} J/psi$ are observed. The measured energy-dependent Born cross section for $e^{+}e^{-} to eta J/psi$ shows an enhancement around 4.2~GeV. The measurement is compatible with an earlier measurement by Belle, but with a significantly improved precision.
The cross section for e^+e^- to pi^+pi^-J/psi between 3.8 and 5.5 GeV/c^2 is measured using a 548 fb^{-1} data sample collected on or near the Upsilon(4S) resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c^2, corresponding to the so called Y(4260), is observed. In addition, there is another cluster of events at around 4.05 GeV/c^2. A fit using two interfering Breit-Wigner shapes describes the data better than one that uses only the Y(4260), especially for the lower mass side of the 4.25 GeV enhancement.
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.
Using data samples with a total integrated luminosity of $20.1~rm fb^{-1}$ collected by the BESIII detector operating at the BEPCII collider, the cross section of the process $e^+e^- rightarrow pi^+pi^-psi(3686)$ is measured at center-of-mass energies between 4.0076 and 4.6984 GeV. The measured cross section is consistent with previous results, but with much improved precision. A fit to the measured energy-dependent cross section, which includes three Breit-Wigner functions and a non-resonant contribution, confirms the existence of the charmonium-like states $Y(4220)$, $Y(4390)$, and $Y(4660)$. This is the first observation of the $Y(4660)$ at the BESIII experiment.
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