The process e+e- to pi+ pi- pi+ pi- pi0 has been studied in the center of mass energy range 1280 -- 1380 MeV using 3.0 1/pb of data collected with the CMD-2 detector in Novosibirsk. Analysis shows that the cross section of the five pion production is dominated by the contributions of the eta pi+pi- and omega pi+pi- intermediate states.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
Axis error includes +- 15/15 contribution.
First results of the study of the process e+e- \to 4\pi by the CMD-2 collaboration at VEPP-2M are presented for the energy range 1.05--1.38 GeV. Using an integrated luminosity of 5.8 pb^{-1}, energy dependence of the processes e+e- \to \pi^+\pi^- 2\pi^0 and e+e- \to 2\pi^+ 2\pi^- has been measured. Analysis of the differential distributions demonstrates the dominance of the a_1\pi and \omega\pi intermediate states. Upper limits for the contributions of other alternative mechanisms are also placed.
Energy dependence of the cross section for the 2PI+ 2PI- final state. Statistical errors only.
Energy dependence of the cross section for the PI+ PI- 2PI0 final state. Statistical errors only.
Energy dependence of the cross section for the OMEGA PI0 final state. Statistical errors only.
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.
No description provided.
No description provided.
No description provided.
In the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider the cross section for the process $e^+e^-\to\eta\pi^+\pi^-$ 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 $e^+e^-\to\eta\pi^+\pi^-$ cross section has been fitted with the vector-meson dominance model. From this fit the product of the branching fractions $B(\rho(1450)\to\eta\pi^+\pi^-)B(\rho(1450)\to e^+e^-)$ has been extracted and compared with the same products for $\rho(1450)\to\omega\pi^0$ and $\rho(1450)\to\pi^+\pi^-$ decays. The obtained cross section data have been also used to test the conservation of vector current hypothesis.
The c.m. energy ($\sqrt{s}$), integrated luminosity ($L$), detection efficiency ($\varepsilon$), number of selected signal events ($N$), radiative-correction factor ($1 + \delta$), measured $e^+e^- \to \eta \pi^+\pi^-$ Born cross section ($\sigma_B$). For the number of events and cross section the statistical error is quoted. The systematic uncertainty on the cross section is 8.3% at $\sqrt{s}<1.45$ GeV, 5.0% at $1.45<\sqrt{s}<1.60$ GeV, and 7.8% at $\sqrt{s}>1.60$ GeV.
None
No description provided.
The cross section of the $e^+e^-\to\omega\pi^0\to\pi^0\pi^0\gamma$ reaction was measured by the SND detector at VEPP-2M $e^+e^-$ collider in the energy range from threshold up to 1.4 GeV. Results of the cross section fitting by the sum of $\rho$, $\rho^{\prime}$ and $\rho^{\prime\prime}$ contributions are presented.
Only statistical errors are presented.
We present a measurement of the $e^+e^-\to K_SK_L$ cross section in the energy range $\sqrt{s}=1.04 \div 1.38$ GeV. For the energy $\sqrt{s}\geq 1.2$ GeV the cross section exceeds vector meson dominance model predictions with only $\rho(770)$, $\omega(783)$, and $\phi(1020)$ mesons taken into account. Measured cross section agrees well with previous measurements.
The Born cross section for the process E+ E- --> KS KL.
The cross section of the process $e^+e^-\to \pi^+\pi^-\pi^0$ was measured in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region $\sqrt[]{s} = 980 \div 1380$ MeV. The measured cross section, together with the $e^+e^-\to \pi^+\pi^-\pi^0$ and $\omega\pi^+\pi^-$ cross sections obtained in other experiments, was analyzed in the framework of the generalized vector meson dominance model. It was found that the experimental data can be described by a sum of $\omega$, $\phi$ mesons and two $\omega^\prime$ and $\omega^{\prime\prime}$ resonances contributions, with masses $m_{\omega^\prime}\sim 1490$,$m_{\omega^{\prime\prime}}\sim 1790$ MeV and widths $\Gamma_{\omega^\prime}\sim 1210$, $\Gamma_{\omega^{\prime\prime}}\sim 560$ MeV. The analysis of the $\pi^+\pi^-$ invariant mass spectra in the energy region $\sqrt[]{s}$ from 1100 to 1380 MeV has shown that for their descriptionone should take into account the $e^+e^-\to\omega\pi^0\to\pi^+\pi^-\pi^0$ mechanism also. The phase between the amplitudes corresponding to the $e^+e^-\to\omega\pi$ and $e^+e^-\to\rho\pi$ intermediate states was measured for the first time. The value of the phase is close to zero and depends on energy.
The measured E+ E- --> PI+ PI- PI0 cross section.
In the experiment with the SND detector at VEPP-2M e^+e^- collider the process $e^+e^-\to\pi^+\pi^-\pi^0$ was studied in the energy range 2E_0 from 1.04 to 1.38 GeV. A broad peak was observed with the visible mass $M_{vis}=1220\pm 20$ MeV and cross section in the maximum $\sigma_0\simeq 4$ nb. The peak can be interpreted as a $\omega$-like resonance $\omega (1200)$.
The total cross section for E+ E- --> PI+ PI- PI0 after correction for efficiency and radiative effects.
The complete results of the experiments carried out with the Neutral Detector at the e + e − storage ring VEPP-2M in the energy range 2 E =0.5–1.4 GeV are reviewed. The data sample corresponds to a total integrated luminosity of 19 pb −1 .
ND results from Dolinsky et al., PL B174 (1986) 453.. Statistical errors only are shown. There is an additional systematic errorof 8%.
Averaged ND data.. Statistical errors only are shown. There is an additional systematic errorof 8%.
Cross section derived from ARGUS data, Albrecht et al., PL B185 (1987) 223.. Statistical errors only are shown. There is an additional systematic errorof 8%.
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