The cross section for the process $e^+e^- \to K^+K^-$ was measured in the energy range $\sqrt{s}$ = 1.04--1.38 GeV in the SND experiment at VEPP-2M $e^+e^-$ collider. The measured cross section is described by the Vector Meson Dominance model with contributions from the light vector mesons $\rho$, $\omega$, $\phi$ and their lowest excitations. The mean statistical accuracy of the measurement is 4.4 %, and the systematic uncertainty is 5.2 %.
The measured cross section and charged kaon form factor.
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.
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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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Using the electron-position storage ring VEPP-2 an experiment has been performed in which the cross-sections of the reactions e + e − → π + π − and e + e − →K + K − were measured in the energy regi on 1.18–1.34 GeV. The experimental values of the formfactors lie higher than curves extrapolated from the ϱ- and ϕ-meson region.
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Results of the measurement of the φ meson parameters with the general purpose detector CMD-2 at the upgraded e + e − collider VEPP-2M at Novosibirsk are presented. This is the first measurement of the four major φ decay modes in a single e + e − experiment. The results based on about 55,600 identified hadronic events are consistent with previous measurements, and have precision comparable to the current world average.
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Using the colliding beam machine, VEPP-2, the excitation curve of the ø-meson resonance was investigated in the three main decay modes. The resonance parameters obtained are the width, the total cross-section and the branching ratios. Namely: Γ = (4.67 ± 0.42) Mev B ( K + K − ) = (54.0 ± 3,4) % σ o = (3.96 ± 0.35) μB B ( K o s K O L ) = (25.7 ±3,0) % B ( e + e − = (2,81 ± 0.25) × 10 −4 B ( π + π − π o ) = (20.3 ± 4,2) %
BREIT-WIGNER FITS TO DATA POINTS AT 9 ENERGIES AROUND PHI FOR EACH CHANNEL. PEAK CROSS SECTIONS QUOTED.
PION FORM FACTOR AT PHI MASS, ALLOWING FOR POSSIBLE INTERFERENCE.
About 300 000 $e^+e^-\to \phi\to K^0_L K^0_S$ events in the center of mass energy range from 984 to 1040 MeV were used for the measurement of the $\phi$ meson parameters. The following results have been obtained: $\sigma_0 = (1367 \pm 15 \pm 21) nb, m_{\phi}=(1019.504 \pm 0.011 \pm 0.033) MeV/c^2, \Gamma_\phi=(4.477 \pm 0.036 \pm 0.022) MeV, \Gamma_{e^+e^-}\cdot B(\phi\to K^0_L K^0_S) = (4.364 \pm 0.048 \pm 0.065)\cdot 10^{-4}$ MeV.
Updated measurements of the E+ E- --> PHI --> K0L K0S measured and 'bare' cross sections for SCAN 1.
Updated measurements of the E+ E- --> PHI --> K0L K0S measured and 'bare' cross sections for SCAN 2.
Updated measurements of the E+ E- --> PHI --> K0L K0S measured and 'bare' cross sections for SCAN 3.
The cross sections of the processes $e^+e^- \to K^+K^-$, $e^+e^- \to K_SK_L$ and $e^+e^- \to \pi^+\pi^-\pi^0$ were measured in the SND experiment at the VEPP-2M collider in the energy region near the $\phi(1020)$ meson. These measurements were based on about $10^6$ $K^+K^-$, $0.5 \times 10^6$ $K_SK_L$ and $0.4 \times 10^6$ $\pi^+\pi^-\pi^0$ selected events. Themeasured cross sections have been analyzed in the framework of the vector meson dominance model and the main parameters of the $\phi$-resonance were obtained, such as its mass, width, the production cross section and branching ratios of the main decay modes. The measured value of the $\phi$ meson total width, $\Gamma_{\phi} = 4.21 \pm 0.04$ is lower than the present world average of $4.458 \pm 0.032$ MeV. Contributions in addition to the conventional vector meson dominance model were found in the $e^+e^- \to \pi^+\pi^-\pi^0$ reaction cross section.
Scan PHI9801 (see text). Point-to-point systematic errors are due to model uncertainty.
Scan PHI9802 (see text). Point-to-point systematic errors are due to model uncertainty.
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