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Register a new userStudy of the process $e^+e^- to etapi^0gamma$ in the energy range $sqrt{s} = mbox{1.05-2.00}$ GeV with the SND detector
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The process $e^+e^-toetapi^0gamma$ is studied in the center-of-mass energy range 1.05-2.00 GeV using data with an integrated luminosity of 94.5 pb$^{-1}$ collected by the SND detector at the VEPP-2000 $e^+e^-$ collider. The $e^+e^-toetapi^0gamma$ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $omegaeta$ intermediate state. The measured cross section of the subprocess $e^+e^-toomegaetatoetapi^0gamma$ is consistent with previous measurements in the $e^+e^-topi^+pi^-pi^0eta$ mode. It is found, with a significance of 5.6$sigma$, that the process $e^+e^-toetapi^0gamma$ is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g. $e^+e^-to a_{0}(1450)gamma$, is measured. It is found to be 15-20 pb in the wide energy range from 1.3 to 1.9 GeV.
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The cross section for the process e+e- --> omega pi0 --> pi0 pi0 gamma has been measured in the energy range 1.05--2.00 GeV. The experiment has been performed at the e+e- collider VEPP-2000 with the SND detector. The measured e+e- --> omega pi0 cross section above 1.4 GeV is the most accurate to date. Below 1.4 GeV our data are in good agreement with the previous SND and CMD-2 measurements. Data on the e+e- --> omega pi0 cross section are well described by the VMD model with two excited rho-like states. From the measured cross section we have extracted the gamma^* --> omega pi0 transition form factor. It has been found that the VDM model cannot describe simultaneously our data and data obtained from the omega --> pi0 mu+ mu- decay. We have also tested CVC hypothesis comparing our results on the e+e- --> omega pi0 cross section with data on the tau- --> omega pi- nu_{tau} decay.
The process $e^+e^-toomegaetapi^0$ is studied in the energy range $1.45-2.00$ GeV using data with an integrated luminosity of 33 pb$^{-1}$ accumulated by the SND detector at the $e^+e^-$ collider VEPP-2000. The $e^+e^-toomegaetapi^0$ cross section is measured for the first time. The cross section has a threshold near 1.75 GeV. Its value is about 2 nb in the energy range $1.8-2.0$ GeV. The dominant intermediate state for the process $e^+e^- to omegaetapi^0$ is found to be $omega a_0(980)$.
In the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider the cross section for the process $e^+e^-toetapi^+pi^-$ has been measured in the center-of-mass energy range from 1.22 to 2.00 GeV. Obtained results are in agreement with previous measurements and have better accuracy. The energy dependence of the $e^+e^-toetapi^+pi^-$ cross section has been fitted with the vector-meson dominance model. From this fit the product of the branching fractions $B(rho(1450)toetapi^+pi^-)B(rho(1450)to e^+e^-)$ has been extracted and compared with the same products for $rho(1450)toomegapi^0$ and $rho(1450)topi^+pi^-$ decays. The obtained cross section data have been also used to test the conservation of vector current hypothesis.
The review of the SND results of the $e^+e^-topi^+pi^-pi^0$ process study in the energy range $sqrt[]{s}=0.42$ -- 1.38 GeV at VEPP-2M collider, based on about $2times 10^6$ selected events, is presented. The total cross section, parameters of the $rho$, $omega$, $phi$ resonances, and $omega^prime$, $omega^{primeprime}$ states were obtained. It was found that $rhopi$ and $omegapi^0$ intermediate states describe the reaction dynamics. 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 the $rhoto 3pi$ decay, suppressed by $G$-parity, with relative probability $B(rhoto 3pi) = (1.01pm^{0.54}_{0.36}pm 0.034) times 10^{-4}$.
The $e^+e^-toetagamma$ cross section has been measured in the center-of-mass energy range 1.07--2.00 GeV using the decay mode $etato 3pi^0$, $pi^0to gammagamma$. The analysis is based on 36 pb$^{-1}$ of integrated luminosity collected with the SND detector at the VEPP-2000 $e^+e^-$ collider. The measured cross section of about 35 pb at 1.5 GeV is explained by decays of the $rho(1450)$ and $phi(1680)$ resonances.
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