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Register a new userObservation of a structure in $e^+e^- to phi eta^{prime}$ at $sqrt{s}$ from 2.05 to 3.08 GeV
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The process $e^{+}e^{-} to phi eta^{prime}$ has been studied for the first time in detail using data sample collected with the BESIII detector at the BEPCII collider at center of mass energies from 2.05 to 3.08 GeV. A resonance with quantum numbers $J^{PC}=1^{--}$ is observed with mass $M$ = (2177.5 $pm$ 4.8 (stat) $pm$ 19.5 (syst)) MeV/${ it{c}^{mathrm{2}}}$ and width $Gamma$ = (149.0 $pm$ 15.6 (stat) $pm$ 8.9 (syst)) MeV with a statistical significance larger than 10$sigma$. The observed structure could be identified with the $phi(2170)$, then the ratio of partial width between the $phi eta^{prime}$ by BESIII and $phi eta$ by BABAR is ($mathcal{B}^{R}_{phi eta}Gamma^{R}_{ee})/{(mathcal{B}^{R}_{phi eta^{prime}}Gamma^{R}_{ee})}$ = 0.23 $pm$ 0.10 (stat) $pm$ 0.18 (syst), which is smaller than the prediction of the $sbar{s}g$ hybrid models by several orders of magnitude.
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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.
We report the first observation of the processes $e^+e^-toUpsilon(rm 1S,2S)eta$ at $sqrt{s}=10.866$~GeV with a $10.2sigma$ and $16.5sigma$ significance respectively. The measured Born cross sections are $sigma(e^+e^- to Upsilon(2S)eta)=2.07 pm 0.21 pm 0.19$~pb, and $sigma(e^+e^- to Upsilon(rm 1S)eta)=0.42 pm 0.08 pm 0.04$~pb. We also set the upper limit on the cross section of the process $e^+e^- to Upsilon(rm 1S)eta^{prime}$ to be $sigma(e^+e^- to Upsilon(rm 1S)eta^{prime})<0.035$~pb at $90%$ CL. The results are obtained with the data sample collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider in the energy range from $10.63$~GeV to $11.02$~GeV.
The cross sections of the process $e^{+}e^{-} to K_{S}^{0}K_{L}^{0}$ are measured at fifteen center-of-mass energies $sqrt{s}$ from $2.00$ to $3.08~{rm GeV}$ with the BESIII detector at the Beijing Electron Positron Collider (BEPCII). The results are found to be consistent with those obtained by BaBar. A resonant structure around $2.2~{rm GeV}$ is observed, with a mass and width of $2273.7 pm 5.7 pm 19.3~{rm MeV}/c^2$ and $86 pm 44 pm 51~{rm MeV}$, respectively, where the first uncertainties are statistical and the second ones are systematic. The product of its radiative width ($Gamma_{e^+e^-}$) with its branching fraction to $K_{S}^{0}K_{L}^{0}$ ($Br_{K_{S}^{0}K_{L}^{0}}$) is $0.9 pm 0.6 pm 0.7~{rm eV}$.
We study the process e+e- to pi+pi-J/psi at a center-of-mass energy of 4.260 GeV using a 525 pb^{-1} data sample collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross section is measured to be (62.9pm 1.9pm 3.7) pb, consistent with the production of the Y(4260). We observe a structure at around 3.9 GeV/c^2 in the pi^pm J/psi mass spectrum, which we refer to as the Z_c(3900). If interpreted as a new particle, it is unusual in that it carries an electric charge and couples to charmonium. A fit to the pi^pm J/psi invariant mass spectrum, neglecting interference, results in a mass of (3899.0pm 3.6pm 4.9) MeV/c^2 and a width of (46pm 10pm 20) MeV. Its production ratio is measured to be R=frac{sigma(e+e- to pi^pm Z_c(3900)^mp to pi+pi-J/psi))} {sigma(e+e- to pi+pi-J/psi)}=(21.5pm 3.3pm 7.5)%. In all measurements the first errors are statistical and the second are systematic.
The cross section of the process $e^{+} e^{-} rightarrow K^{+} K^{-}$ is measured at a number of center-of-mass energies $sqrt{s}$ from 2.00 to 3.08 GeV with the BESIII detector at the Beijing Electron Positron Collider (BEPCII). The results provide the best precision achieved so far. A resonant structure around 2.2 GeV is observed in the cross section line shape. A Breit-Wigner fit yields a mass of $M=2239.2 pm 7.1 pm 11.3$~and a width of $Gamma=139.8pm12.3pm20.6$ MeV, where the first uncertainties are statistical and the second ones are systematic. In addition, the time-like electromagnetic form factor of the kaon is determined at the individual center-of-mass energy points.
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