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Register a new userObservation of $e^+ e^- to eta Y(2175)$ at center-of-mass energies above 3.7$sim$GeV
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The state $Y(2175)$ is observed in the process $e^+ e^- to eta Y(2175)$ at center-of-mass energies between 3.7 and 4.6$sim$GeV with a statistical significance larger than $10sigma$ using data collected with the BESIII detector operating at the BEPCII storage ring. This is the first observation of the $Y(2175)$ in this process. The mass and width of the $Y(2175)$ are determined to be ($2135pm 8pm 9$)~MeV/$c^2$ and ($104pm 24pm 12$)~MeV, respectively, and the production cross section of $e^+ e^- to eta Y(2175)to etaphi f_{0}(980)to etaphi pi^+ pi^-$ is at a several hundred femtobarn level. No significant signal for the process $e^+ e^- to eta Y(2175)$ is observed and the upper limit on $sigma(e^+ e^- to eta Y(2175))/sigma(e^+ e^- to eta Y(2175))$ is estimated to be 0.43 at the 90% confidence level. We also search for $psi(3686) to eta Y(2175)$. No significant signal is observed, indicating a strong suppression relative to the corresponding $J/psi$ decay, in violation of the 12% rule.
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We observe for the first time the process $e^{+}e^{-} rightarrow eta h_c$ with data collected by the BESIII experiment. Significant signals are observed at the center-of-mass energy $sqrt{s}=4.226$ GeV, and the Born cross section is measured to be $(9.5^{+2.2}_{-2.0} pm 2.7)$ pb. Evidence for $eta h_c$ is observed at $sqrt{s}=4.358$ GeV with a Born cross section of $(10.0^{+3.1}_{-2.7} pm 2.6)$ pb, and upper limits on the production cross section at other center-of-mass energies between 4.085 and 4.600 GeV are determined.
The process $e^{+}e^{-}to eta^{prime} J/psi$ is observed for the first time with a statistical significance of $8.6sigma$ at center-of-mass energy $sqrt{s} = 4.226$ GeV and $7.3sigma$ at $sqrt{s} = 4.258$ GeV using data samples collected with the BESIII detector. The Born cross sections are measured to be $(3.7 pm 0.7 pm 0.3)$ and $(3.9 pm 0.8 pm 0.3)$ pb at $sqrt{s} = 4.226$ and $4.258$ GeV, respectively, where the first errors are statistical and the second systematic. Upper limits at the 90% confidence level of the Born cross sections are also reported at other 12 energy points.
Using a total of $5.25~{rm fb}^{-1}$ of $e^{+}e^{-}$ collision data with center-of-mass energies from 4.236 to 4.600 GeV, we report the first observation of the process $e^{+}e^{-}to etapsi(2S)$ with a statistical significance of $5sigma$. The data sets were collected by the BESIII detector operating at the BEPCII storage ring. We measure the yield of events integrated over center-of-mass energies and also present the energy dependence of the measured cross section.
Using a 478 pb$^{-1}$ data sample collected with the BESIII detector operating at the BEPCII storage ring at a center-of-mass energy of $sqrt{s}=4.009$ GeV, the production of $e^{+}e^{-}to eta Jpsi$ is observed for the first time with a statistical significance of greater than $10sigma$. The Born cross section is measured to be $(32.1pm 2.8 pm 1.3)$ pb, where the first error is statistical and the second systematic. Assuming the $eta Jpsi$ signal is from a hadronic transition of the $psi(4040)$, the fractional transition rate is determined to be ${cal B}(psi(4040)to eta Jpsi)=(5.2pm 0.5pm 0.2pm 0.5)times 10^{-3}$, where the first, second, and third errors are statistical, systematic, and the uncertainty from the $psi(4040)$ resonant parameters, respectively. The production of $e^{+}e^{-} to pi^0 Jpsi$ is searched for, but no significant signal is observed, and ${cal B}(psi(4040)to pi^0 Jpsi) < 2.8 times 10^{-4}$ is obtained at the 90% confidence level.
Based on $14.7~textrm{fb}^{-1}$ of $e^+e^-$ annihilation data collected with the BESIII detector at the BEPCII collider at 17 different center-of-mass energies between $3.7730~textrm{GeV}$ and $4.5995~textrm{GeV}$, Born cross sections of the two processes $e^+e^- to pbar{p}eta$ and $e^+e^- to pbar{p}omega$ are measured for the first time. No indication of resonant production through a vector state $V$ is observed, and upper limits on the Born cross sections of $e^+e^- to V to pbar{p}eta$ and $e^+e^- to V to pbar{p}omega$ at the $90%$ confidence level are calculated for a large parameter space in resonance masses and widths. For the current world average parameters of the $psi(4230)$ of $m=4.2187~textrm{GeV}/c^{2}$ and $Gamma=44~textrm{MeV}$, we find upper limits on resonant production of the $pbar{p}eta$ and $pbar{p}omega$ final states of $7.5~textrm{pb}$ and $10.4~textrm{pb}$ at the $90%$ CL, respectively.
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