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Register a new userObservation of $e^+e^- to pi^+ pi^- pi^0 chi_{bJ}$ and search for $X_b to omega Upsilon(1S)$ at $sqrt{s}sim 10.867$ GeV
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The $e^+e^- to pi^+ pi^- pi^0 chi_{bJ}$ ($J=0,~1,~2$) processes are studied using a 118~fb$^{-1}$ data sample collected at a center-of-mass energy of 10.867 GeV, in the $Upsilon(10860)$ energy range, with the Belle detector. The $pi^+ pi^- pi^0 chi_{b1}$, $pi^+pi^-pi^0chi_{b2}$, $omegachi_{b1}$ signals and the evidence of $omegachi_{b2}$ are observed for the first time and the cross sections are measured. No significant $pi^+pi^-pi^0chi_{b0}$ or $omegachi_{b0}$ signal is observed and 90% confidence level upper limits on the cross sections for these two processes are obtained. In the $pi^+pi^-pi^0$ invariant mass spectrum, significant non-$omega$ signals are also observed. We search for the $X(3872)$-like state with a hidden $bbar{b}$ component (named $X_b$) decaying into $omega Upsilon(1S)$; no significant signal is observed with a mass between $10.55$ and $10.65$ GeV/$c^2$.
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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 $e^+e^-to pi^+pi^-pi^0$ was measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2M collider in the energy region $sqrt[]{s}$ below 980 MeV. This measurement was based on about $1.2 times 10^6$ selected events. The obtained cross section was analyzed together with the SND and DM2 data in the energy region $sqrt[]{s}$ up to 2 GeV. The $omega$-meson parameters: $m_omega=782.79pm 0.08pm 0.09$ MeV, $Gamma_omega=8.68pm 0.04pm 0.15$ MeV and $sigma(omegato 3pi)=1615pm 9pm 57$ nb were obtained. It was found that the experimental data cannot be described by a sum of only $omega$, $phi$, $omega^prime$ and $omega^{primeprime}$ resonances contributions. This can be interpreted as a manifestation of $rhoto 3pi$ decay, suppressed by $G$-parity, with relative probability $B(rhoto 3pi) = (1.01pm^{0.54}_{0.36}pm 0.034) times 10^{-4}$.
Using $e^{+}e^{-}$ collision data collected with the BESIII detector at the BEPCII collider corresponding to an integrated luminosity of 5.2 $fb^{-1}$ at center-of-mass energies ($sqrt{s}$) from 4.009 to 4.600 GeV, the process $e^{+}e^{-} to pi^{0} pi^{0}psi(3686)$ is studied for the first time. The corresponding Born cross sections are measured and found to be half of those of the reaction $e^{+}e^{-} to pi^{+}pi^{-}psi(3686)$. This is consistent with the expectation from isospin symmetry. Furthermore, the Dalitz plots for $pi^{0}pi^{0}psi(3686)$ are accordant with those of $pi^{+}pi^{-}psi(3686)$ at all energy points, and a neutral analogue to the structure in $pi^pm psi(3686)$ around 4040 MeV/$c^{2}$ first observed at $sqrt{s}$=4.416 GeV is observed in the isospin neutral mode at the same energy.
The cross section of the process $e^+e^-to pi^+pi^-pi^0$ was measured in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region $sqrt[]{s} = 980 div 1380$ MeV. The measured cross section, together with the $e^+e^-to pi^+pi^-pi^0$ and $omegapi^+pi^-$ cross sections obtained in other experiments, was analyzed in the framework of the generalized vector meson dominance model. It was found that the experimental data can be described by a sum of $omega$, $phi$ mesons and two $omega^prime$ and $omega^{primeprime}$ resonances contributions, with masses $m_{omega^prime}sim 1490$,$m_{omega^{primeprime}}sim 1790$ MeV and widths $Gamma_{omega^prime}sim 1210$, $Gamma_{omega^{primeprime}}sim 560$ MeV. The analysis of the $pi^+pi^-$ invariant mass spectra in the energy region $sqrt[]{s}$ from 1100 to 1380 MeV has shown that for their descriptionone should take into account the $e^+e^-toomegapi^0topi^+pi^-pi^0$ mechanism also. The phase between the amplitudes corresponding to the $e^+e^-toomegapi$ and $e^+e^-torhopi$ intermediate states was measured for the first time. The value of the phase is close to zero and depends on energy.
The process $e^+e^- to pi^+pi^-pi^0eta$ is studied in the center-of-mass energy region below 2 GeV with the SND detector at the VEPP-2000 $e^+e^-$ collider. The four intermediate states contribute to this process: $omegaeta$, $phieta$, $a_0(980)rho$, and a structureless $pi^+pi^-pi^0eta$ state. We measure the total $e^+e^- to pi^+pi^-pi^0eta$ cross section and the cross sections for its components: $omegaeta$, $phieta$, and a sum of $a_0(980)rho$ and the structureless state. Our results are in agreement with previous measurements and have comparable or better accuracies.
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