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Register a new userStudy of $e^+e^- rightarrow pi^{0}X(3872)gamma$ and search for $Z_c(4020)^{0}rightarrow X(3872)gamma$
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Using data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.178 to 4.600 GeV, we study the process $e^+e^-rightarrowpi^{0}X(3872)gamma$ and search for $Z_c(4020)^{0}rightarrow X(3872)gamma$. We find no significant signal and set upper limits on $sigma(e^+e^-rightarrowpi^{0}X(3872)gamma)cdotmathcal{B}(X(3872)rightarrowpi^{+}pi^{-}J/psi)$ and $sigma(e^+e^-rightarrowpi^{0}Z_c(4020)^{0})cdotmathcal{B}(Z_c(4020)^{0}rightarrow X(3872)gamma)cdotmathcal{B}(X(3872)rightarrowpi^{+}pi^{-}J/psi)$ for each energy point at $90%$ confidence level, which is of the order of several tenths pb.
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We report the results of a search for the decay $B^0 to X(3872)(to J/psi pi^+ pi^-) gamma$. The analysis is performed on a data sample corresponding to an integrated luminosity of $711,{rm fb}^{-1}$ and containing $772 times 10^6 Bbar{B}$ pairs, collected with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider running at the $Upsilon(4S)$ resonance energy. We find no evidence for a signal and place an upper limit of $mathcal{B}(B^0 to X(3872)gamma)times mathcal{B}(X(3872) to J/psi pi^+ pi^-) < 5.1 times 10^{-7}$ at 90% confidence level.
Results of a study of the $K^+ rightarrow pi^{0} e^{+} u gamma $ decay at OKA setup are presented. More than 32000 events of this decay are observed. The differential spectra over the photon energy and the photon-electron opening angle in kaon rest frame are presented. The branching ratios, normalized to that of $K_{e3}$ decay are calculated for different cuts in $E^*_gamma$ and $cosTheta^{*}_{egamma}$. In particular, the branching ratio for $E^{*}_{gamma}>30$ MeV and $Theta^{*}_{e gamma}>20^{circ}$ is measured R = $frac{Br(K^+ rightarrow pi^{0} e^{+} u_{e} gamma) } {Br(K^+ rightarrow pi^{0} e^{+} u_{e})} $ = =(0.587$pm$0.010($stat.$)$pm$0.015($syst.$))$times10^{-2}$, which is in a good agreement with ChPT $O(p^{4})$ calculations.
With data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.009 to 4.420 GeV, the process $e^{+} e^{-} to gamma X(3872)$ is observed for the first time with a statistical significance of $6.3sigma$. The measured mass of the $X(3872)$ is ($3871.9pm 0.7_{rm stat.}pm 0.2_{rm sys.}$) MeV/$c^2$, in agreement with previous measurements. Measurements of the product of the cross section $sigma[e^{+} e^{-} to gamma X(3872)]$ and the branching fraction $mathcal{B}[X(3872) to pi^{+} pi^{-} J/psi]$ at center-of-mass energies 4.009, 4.229, 4.260, and 4.360 GeV are reported. Our measurements are consistent with expectations for the radiative transition process $Y(4260) to gamma X(3872)$.
Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of $sqrt{s}=4.23$, 4.26, and 4.36~GeV, we observe $EEto pphc$ for the first time. The Born cross sections are measured and found to be about half of those of $EEto pi^+pi^-h_c$ within less than 2$sigma$. In the $pi^0h_c$ mass spectrum, a structure at 4.02~GeV/$c^2$ is found. It is most likely to be the neutral isospin partner of the $zcp^{pm}$ observed in the process of $EEto pi^+pi^-h_c$ is found. A fit to the $pi^0 h_c$ invariant mass spectrum, with the width of the $zcpn$ fixed to that of its charged isospin partner and possible interferences with non-$zcpn$ amplitudes neglected, gives a mass of ($4023.9pm 2.2 pm 3.8$)~MeV/$c^2$ for the $zcpn$, where the first error is statistical and the second systematic.
The cross sections of $e^+e^- rightarrow pi Z_c(3900) rightarrow pipi J/psi$ and $e^+e^- rightarrow pi Z_c(3900) rightarrow pi Dbar{D}^{*}$ have been measured by BESIII experiment. We try to perform a combined fit to the cross sections with one Breit-Wigner function, the fit results show the structures mass and width are $M=(4232pm5)$ MeV/$c^2$, $Gamma=(65pm21)$ MeV. The ratio $frac{mathcal{B}(Z_c(3900)rightarrow Dbar{D}^{*})}{mathcal{B}(Z_c(3900)rightarrowpi J/psi)}$ is determined to be $(16pm6)$. We also try to fit the cross sections with two Breit-Wigner functions, while we cant come to any definitive conclusions about the second structure. More measurements are desired to improve the understanding of $e^+e^- rightarrow pi Z_c(3900)$ line shape.
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