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تسجيل مستخدم جديدStudy of $Delta(1232)$ isobar electroproduction at VEPP-2M $e^+e^-$ collider
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Results from the Spherical Nonmagnetic Detector (SND) on $Delta (1232)$ isobar electroproduction in the collisions of beam electrons (positrons) and residual gas nuclei in the VEPP-2M $e^+e^-$ collider are presented. On the basis of the obtained data the expected counting rate of this process in future high luminosity $e^+e^-$ colliders (~$phi$-, $c$-$tau$- and $b$-factories) was estimated.
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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 b
y 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.
Results of the SND experiment at the VEPP-2M e+ e- collider on the QED processes e+ e- --> e+ e- gamma and e+ e- --> e+ e- gamma gamma with production at large angles are presented. Energy and angular distributions of the final particles were studied
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