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Register a new userStudy of the $rho$, $omega$, $phitoetagammato 7gamma$ Decays with an SND Detector on a VEPP-2M Collider
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The $e^+e^-toetagammato 7gamma$ process was studied in the energy range $2E=600div 1060$ MeV with an SND detector on a VEPP-2M $e^+e^-$ collider. The decay branching ratios $B(phitoetagamma)=(1.343pm 0.012pm 0.055)cdot 10^{-2}$, $B(omegatoetagamma)=(4.60pm 0.72pm 0.19)cdot 10^{-4}$, and $B(rhotoetagamma)=(2.69pm 0.32pm 0.16)cdot 10^{-4}$ were measured.
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Short overview of experiments with SND detector at VEPP-2M e^+e^- collider in the energy range 2E = 400 - 1400 MeV and preliminary results of data analysis are presented.
In experiment with the SND detector at VEPP-2M $e^+e^-$ collider the $e^+e^-toetagamma$ cross section was measured in the energy range $E$=0.60--1.38 GeV with the integrated luminosity of 27.8 pb$^{-1}$. The measured cross section is well described by the vector meson dominance model with contributions from the $rho(770)$, $omega(783)$, $phi(1020)$, $rho^{prime}(1465)$ resonances and agrees with results of previous measurements. The decay probabilities $BR(phitoetagamma)$, $BR(omegatoetagamma)$ and $BR(rhotoetagamma)$ were measured with the accuracies better than or comparable to the world averages.
The process $e^+e^- to pi^0gamma$ has been studied in the experiment with the SND detector at the VEPP-2M $e^+e^-$ collider. The $e^+e^- to pi^0gamma$ cross section has been measured in the center-of-mass energy range from 0.60 to 1.38 GeV. The cross section is well described by the vector meson dominance model. From the fit to the cross section data we have determined the branching fractions $B(rhotopi^0gamma)=(4.20pm0.52)times10^{-4}$, $B(omegatopi^0gamma)=(8.88pm0.18)%$, $B(phitopi^0gamma)=(1.367pm0.072)times10^{-3}$, and the relative phase between the $rho$ and $omega$ amplitudes $varphi_{rho}=(-12.7pm4.5)^circ$. Our data on the process $e^+e^- to pi^0gamma$ are the most accurate to date.
The current status of experiments with SND detector at VEPP-2M $e^+e^-$ collider in the energy range $2E_0=0.4-1.4$ GeV is given. The new results of analysis of $phi$ decay into $pi^0pi^0gamma$, $etapi^0gamma$ are based on the full SND statistics corresponding 20 million of $phi$ decay. New measurement of $omegatopi^0pi^0gamma$ decay and a first observation of $rhotopi^0pi^0gamma$ are presented. The accuracy of many other rare decays of light vector mesons was improved. In the energy range $2E_0=1.0div1.4$ GeV the cross sections of the processes $e^+e^-toomegapi^0$ and $e^+e^-topi^+pi^-pi^0$ were measured. The results of the fitting of data are discussed.
The paper describes experiments with the SND detector at VEPP-2M collider, carried out during the period from October 1995 until June 1997. The total integrated luminosity of 6.4 pb^{-1} was collected in the energy range 2E=0.4-1.4 GeV (MHAD97 experiment), corresponding to 4*10^5 mu^+ mu^- pairs produced. Preliminary results of the 1996 phi-meson experiment (FI96) are presented. The total number of phi-mesons produced is 4*10^6. New data on rare decays of phi and eta (550) mesons, in particular B(phi -> eta gamma) = (1.30+-0.06+-0.07)%, B(phi -> pi^0 pi^0 gamma) = (1.1+-0.2)*10^{-4}, (M_{pi^0 pi^0} > 800 MeV), B(phi -> f^0 gamma) = (4.7+-1.0)*10^{-4}, B(phi -> eta pi^0 gamma) = (1.3+-0.5)*10^{-4}, B(phi -> eta gamma) < 1.7*10^{-4}, B(phi -> 2 pi^0 ) < 6*10^{-4} were obtained.
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