In experiment with the SND detector at VEPP-2M $e^+e^-$ collider the $e^+e^-\to\eta\gamma$ 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 $\BR(\phi\to\eta\gamma)$, $\BR(\omega\to\eta\gamma)$ and $\BR(\rho\to\eta\gamma)$ were measured with the accuracies better than or comparable to the world averages.
Cross section from the ETA --> 3PI0 decay mode.
Cross section from the ETA --> PI+ PI- PI0 decay mode.
The cross section of the process e+e-\to\mu+\mu- was measured in the SND experiment at the VEPP-2M e+e- collider in the energy region \sqrt{s}=980, 1040 -- 1380 MeV. The event numbers of the process e+e-\to\mu+\mu- were normalized to the integrated luminosity measured using e+e-\to e+e- and e+e-\to\gamma\gamma processes. The ratio of the measured cross section to the theoretically predicted value is 1.006\pm 0.007 \pm 0.016 and 1.005 \pm 0.007 \pm 0.018 in the first and second case respectively. Using results of the measurements, the electromagnetic running coupling constant \alpha in the energy region \sqrt{s}=1040 -- 1380 MeV was obtained <1/\alpha> = 134.1\pm 0.5 \pm 1.2 and this is in agreement with theoretical expectation.
The E+ E- --> MU+ MU- cross section obtained using the (GAMMA GAMMA) luminosity measurement.
The measured E+ E- --> E+ E- cross section in the electron angle 30 to 150 degrees.
The cross section of the process $e^+ e^-\to\pi^+\pi^-$ 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 $m_\rho = 775.3\pm 0.5\pm 0.6$ MeV, $\Gamma_\rho = 145.6\pm 0.6\pm 0.8$ MeV, $B_{\rho\to e^+ e^-}\times B_{\rho\to\pi^+\pi^-} = (4.89\pm 0.02\pm 0.04)\times 10^{-5}$, and the parameters of the $e^+ e^-\to\omega\to\pi^+\pi^-$ process, suppressed by $G$-parity, as $B_{\omega\to e^+ e^-}\times B_{\omega\to\pi^+\pi^-}= (1.32\pm 0.06\pm 0.02)\times 10^{-6} $ and $\phi_{\rho\omega} = 110.7\pm 1.5\pm1.0$ degrees.
The Born cross section of the process e+e- -> pi+pi- taking into account the radiative corrections due to the initial and final state radiation.
Measured value of the pion form factor
The bare e+e- -> pi+pi- undressed cross without vacuum polarization, but with the final state radiative correction.
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 cross section of the process $e^+e^-\to \pi^+\pi^-\pi^0$ was measured in the Spherical Neutral Detector (SND) experiment at the VEPP-2M collider in the energy region $\sqrt[]{s}$ below 980 MeV. This measurement was based on about $1.2 \times 10^6$ selected events. The obtained cross section was analyzed together with the SND and DM2 data in the energy region $\sqrt[]{s}$ up to 2 GeV. The $\omega$-meson parameters: $m_\omega=782.79\pm 0.08\pm 0.09$ MeV, $\Gamma_\omega=8.68\pm 0.04\pm 0.15$ MeV and $\sigma(\omega\to 3\pi)=1615\pm 9\pm 57$ nb were obtained. It was found that the experimental data cannot be described by a sum of only $\omega$, $\phi$, $\omega^\prime$ and $\omega^{\prime\prime}$ resonances contributions. This can be interpreted as a manifestation of $\rho\to 3\pi$ decay, suppressed by $G$-parity, with relative probability $B(\rho\to 3\pi) = (1.01\pm^{0.54}_{0.36}\pm 0.034) \times 10^{-4}$.
Measurements of the E+ E- --> PI+ PI- PI0 cross section.
In the study of the reaction $e^+e^-\to K_{S}K_{L}$ at the VEPP-2M $e^+e^-$ collider with the SND detector the nuclear interaction length of $K_{L}$ meson in NaI(Tl) has been measured. Its value is found to be 30--50 cm in the $K_{L}$ momentum range 0.11--0.48 GeV/$c$. The results are compared with the values used in the simulation programs GEANT4 and UNIMOD.
The energy interval ($\sqrt{s}$), integrated luminosity ($IL$), number of selected events ($N$), number of background events ($N_{\rm bkg}$), number of events with five or more photons ($N_{5\gamma}$, $N_{5\gamma,{\rm bkg}}$), and the measured $K_L$ nuclear interaction length in NaI(Tl) ($\lambda_{\rm int}$).
Results of the study of the e+e-->pi0 gamma process with SND detector at VEPP-2M collider in the c.m.s. energy range sqrt(s)=0.60-0.97 GeV are presented. Using 36513 selected events corresponding to a total integrated luminosity of 3.4 pb^-1 the e+e-->pi0 gamma cross section was measured. The energy dependence of the cross section was analyzed in the framework of the vector meson dominance model. The data are well described by a sum of phi,omega,rho0->pi0 gamma decay contributions with measured decay probabilities: Br(omega->pi0 gamma)=(9.34+-0.15+-0.31)% and Br(rho0->pi0 gamma)=(5.15+-1.16+-0.73)*10^-4 . The rho-omega relative interference phase is phi(rho,omega}=(-10.2+-6.5+-2.5) degree.
Measured E+ E- --> PI0 GAMMA cross section.
Total cross section into OMEGA and RHO0 channels.
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.
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 processes$e^+e^-\rightarrow\eta\gamma, \pi^0\gamma\rightarrow 3\gamma$were studied in the SND experiment at the VEPP-2M collider in the energy region of the
Results of energy scan of the cross section.
Cross sections for PHI production and decay into the two states from a fit to the data at the peak.
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