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Register a new userMeasurement of the $e^+e^- topi^+pi^- $ process cross section with the SND detector at the VEPP-2000 collider in the energy region $0.525<sqrt{s}<0.883$ GeV
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The cross section of the process $e^+ e^-topi^+pi^-$ has been measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2000 $e^+e^-$ collider VEPP-2000 in the energy region $525 <sqrt[]{s} <883$ MeV. The measurement is based on data with an integrated luminosity of about 4.6 pb$^{-1}$. The systematic uncertainty of the cross section determination is 0.8 % at $sqrt{s}>0.600$ GeV. The $rho$ meson parameters are obtained as $m_rho = 775.3pm 0.5pm 0.6$ MeV, $Gamma_rho = 145.6pm 0.6pm 0.8$ MeV, $B_{rhoto e^+ e^-}times B_{rhotopi^+pi^-} = (4.89pm 0.02pm 0.04)times 10^{-5}$, and the parameters of the $e^+ e^-toomegatopi^+pi^-$ process, suppressed by $G$-parity, as $B_{omegato e^+ e^-}times B_{omegatopi^+pi^-}= (1.32pm 0.06pm 0.02)times 10^{-6} $ and $phi_{rhoomega} = 110.7pm 1.5pm1.0$ degrees.
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The $e^+e^- to etapi^+pi^-$ cross section is measured at the SND detector in the $eta$ decay mode $etato 3pi^0$. The analysis is based on the data sample with an integrated luminosity of 32.7 pb$^{-1}$ collected at the VEPP-2000 $e^+e^-$ collider in the center-of-mass energy range $sqrt{s}=1.075-2.000$ GeV. The data obtained in the $etato 3pi^0$ decay mode are found to be in agreement with the previous SND measurements in the $etato gammagamma$ mode. Therefore the measurements in the two modes are combined.
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 cross section of the process $e^{+}e^{-}rightarrowetapi^{+}pi^{-}$ is measured using the data collected with the CMD-$3$ detector at the VEPP-$2000$ collider in the center-of-mass energy range from $1.1$ to $2.0$ GeV. The decay mode $etarightarrowgammagamma$ is used for $eta$ meson reconstruction in the data sample corresponding to an integrated luminosity of $78.3$ pb$^{-1}$. The energy dependence of the $e^{+}e^{-}rightarrowetapi^{+}pi^{-}$ cross section is fitted within the framework of vector meson dominance in order to extract the $Gamma(rho(1450)rightarrow{^{+}e^{-}})mathcal{B}(rho(1450)rightarrowetapi^{+}pi^{-})$ and the $Gamma(rho(1700)rightarrow{e^{+}e^{-}})mathcal{B}(rho(1700)rightarrowetapi^{+}pi^{-})$ products. Based on conservation of vector current, the analysed data are used to test the relationship between the $e^{+}e^{-}rightarrowetapi^{+}pi^{-}$ cross section and the spectral function in $tau^-rightarrowetapi^-pi^0 u_tau$ decay. The $e^{+}e^{-}rightarrowetapi^{+}pi^{-}$ cross section measured with the CMD-$3$ detector is in good agreement with the previous measurements.
The corrected cross section of the e^+e^-topi^+pi^- process measured in the SND experiment at the VEPP-2M e^+e^- collider is presented. The update is necessary due to a flaw in the e^+e^-topi^+pi^- and e^+e^-tomu^+mu^- Monte Carlo events generators used previously in data analysis.
The process $e^+e^- to K^+K^-pi^+pi^-$ has been studied in the center-of-mass energy range from 1500 to 2000,MeV using a data sample of 23 pb$^{-1}$ collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider. Using about 24000 selected events, the $e^+e^- to K^+K^-pi^+pi^-$ cross section has been measured with a systematic uncertainty decreasing from 11.7% at 1500-1600,MeV to 6.1% above 1800,MeV. A preliminary study of $K^+K^-pi^+pi^-$ production dynamics has been performed.
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