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Register a new userEvidence for $e^{+}e^{-} to gammaeta_c(1S)$ at center-of-mass energies between 4.01 and 4.60 GeV
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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$sigma$.
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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 $e^+e^-togammachi_{cJ}$ ($J=0,1,2$) processes are studied at center-of-mass energies ranging from 3.773 to 4.600~GeV, using a total integrated luminosity of 19.3~fb$^{-1}$ $e^+e^-$ annihilation data accumulated with the BESIII detector at BEPCII. We observe for the first time $e^+e^-togamma chi_{c1,c2}$ signals at $sqrt{s}=$ 4.180~GeV with statistical significances of 7.6$sigma$ and 6.0$sigma$, respectively. The production cross section of $e^+e^-togamma chi_{c1,c2}$ at each center-of-mass energy is also measured. We find that the line shape of the $e^+e^-togamma chi_{c1}$ cross section can be described with conventional charmonium states $psi(3686)$, $psi(3770)$, $psi(4040)$, $psi(4160)$. Compared with this, for the $e^+e^-togamma chi_{c2}$ channel, one more additional resonance is added to describe the cross section line shape. Its mass and width are measured to be $M=4371.7pm7.5pm1.8$~MeV/$c^2$ and $Gamma^{tot}=51.1pm17.6pm1.9$~MeV, where the first uncertainties are statistical and the second systematic. The significance of this resonance is estimated to be 5.8$sigma$, and its parameters agree with the $Y(4360)$ resonance previously reported in $e^+e^-topi^+pi^-psi(3686)$, and the $Y(4390)$ in $e^+e^-topi^+pi^-h_c$ within uncertainties. No significant signal for the $e^+e^-togamma chi_{c0}$ process is observed, and the upper limits of Born cross sections $sigma_{B}(e^+e^-togamma chi_{c0})$ at 90% confidence level are reported.
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 collected at center-of-mass energies of $sqrt{s}$ = 4.009, 4.230, 4.260, and 4.360 GeV with the BESIII detector operating at the BEPCII collider, we perform a search for the process $e^+e^-togammachi_{cJ}$ $(J = 0, 1, 2)$ and find evidence for $e^+e^-togammachi_{c1}$ and $e^+e^-togammachi_{c2}$ with statistical significances of 3.0$sigma$ and 3.4$sigma$, respectively. The Born cross sections $sigma^{B}(e^+e^-togammachi_{cJ})$, as well as their upper limits at the 90% confidence level are determined at each center-of-mass energy.
Using data taken at 23 center-of-mass energies between 4.0 and 4.6 GeV with the BESIII detector at the BEPCII collider and with a total integrated luminosity of approximately $15$ fb$^{-1}$, the process $e^+e^-to 2(p bar{p})$ is studied for the first time. The Born cross sections for $e^+e^-to 2(p bar{p})$ are measured, and no significant structure is observed in the lineshape. The baryon pair ($pp$ and $bar{p}bar{p}$) invariant mass spectra are consistent with phase space, therefore no hexaquark or di-baryon state is found.
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