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Register a new userSearch for the process $e^+e^-to J/psi + X(1835)$ at $sqrt{s}approx10.6$GeV
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We report the results of a search for the $X(1835)$ state in the process $e^+e^-to J/psi+X(1835)$ using a data sample of 672 fb$^{-1}$ collected with the Belle detector at and near the $Upsilon(4S)$ resonance at the KEKB asymmetric-energy $e^+e^-$ collider. No significant evidence is found for this process, and an upper limit is set on its cross section times the branching fraction: $sigma_{rm Born}(e^+e^- to J/psi X(1835)) cdot$ {${cal B}(X(1835)to ge 3$ charged tracks)} $< 1.3 {rm fb}$ at 90% confidence level.
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Using data samples collected at center-of-mass energies $sqrt{s} = 4.23$, 4.26, and 4.36 GeV with the BESIII detector operating at the BEPCII storage ring, we search for the production of the charmoniumlike state $Y(4140)$ through a radiative transition followed by its decay to $phi J/psi$. No significant signal is observed and upper limits on $sigma[e^{+} e^{-} rightarrow gamma Y(4140)] cdot mathcal{B}(Y(4140)rightarrow phi J/psi)$ at the $90%$ confidence level are estimated as 0.35, 0.28, and 0.33 pb at $sqrt{s} = 4.23$, 4.26, and 4.36 GeV, respectively.
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.
Using a sample of $2.25times 10^8$ $J/psi$ events collected with the BESIII detector at the BEPCII collider, we search for the $J/psi$ semi-leptonic weak decay $J/psi to D^{-}_{s} e^{+} u_{e}+c.c.$ with a much higher sensitivity than previous searches. We also perform the first search for $J/psi to D^{*-}_{s} e^{+} u_{e}+c.c.$ No significant excess of a signal above background is observed in either channel. At the $90%$ confidence level, the upper limits are determined to be $mathcal{B}(J/psi to D^{-}_{s}e^{+} u_{e}+c.c.)<1.3times10^{-6}$ and $mathcal{B}(J/psi to {D^{*}_{s}}^{-}e^{+} u_{e}+c.c.)<1.8times10^{-6}$, respectively. Both are consistent with Standard Model predictions.
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.
Using a data sample of $448.1times10^6$ $psi(3686)$ events collected at $sqrt{s}=$ 3.686 GeV with the BESIII detector at the BEPCII, we search for the rare decay $J/psi to phi e^+ e^-$ via $psi(3686) to pi^+pi^- J/psi $. No signal events are observed and the upper limit on the branching fraction is set to be $mathcal{B}(J/psi to phi e^+ e^-) < 1.2 times 10^{-7}$ at the 90% confidence level, which is still about one order of magnitude higher than the Standard Model prediction.
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