The process $e^+e^-{\to}K^+K^-\eta$ has been studied in the center-of-mass
energy range from 1.59 to 2.007\,GeV using the data sample of 59.5 pb$^{-1}$,
collected with the CMD-3 detector at the ...VEPP-2000 $e^+e^-$ collider in 2011,
2012 and 2017. The $K^+K^-\eta$ final state is found to be dominated by the
contribution of the $\phi(1020)\eta$ intermediate state. The cross section of
the process $e^+e^-{\to}\phi(1020)\eta$ has been measured with a systematic
uncertainty of 5.1$\%$ on the base of 3009 $\pm$ 67 selected events. The
obtained cross section has been used to calculate the contribution to the
anomalous magnetic moment of the muon: $a_{\mu}^{\phi\eta}(E<1.8\, {\rm
GeV})=(0.321 \pm 0.015_{\rm stat} \pm 0.016_{\rm syst}) \times 10^{-10}$,
$a_{\mu}^{\phi\eta}(E<2.0\, {\rm GeV})=(0.440 \pm 0.015_{\rm stat} \pm
0.022_{\rm syst}) \times 10^{-10}$. From the cross section approximation the
$\phi(1680)$ meson parameters have been determined with better statistical
precision, than in previous studies.
The first results of the luminosity measurement with the CMD-3 detector at the VEPP-2000 e+e− collider are presented. The luminosity was measured using two different processes e+e−→e+e− and e+e−→γγ, ...that allowed to better understand and estimate the systematic accuracy which was found to be ∼2%. The analysis of the data was done on the integrated luminosity about 20 pb−1. A Monte-Carlo Generator Photon Jets (MCGPJ) A.Arbuzov et al., EPJ C46, 689 (2006); S.Actis et al., EPJ C66, 585 (2010) to simulate Bhabha scattering events as well as production of two photons was adopted for analysis of the data. A theoretical precision of these cross sections with radiative corrections (RC) is estimated to be better than 0.2%.
The process $e^+e^- \to K^+K^-$ has been studied using $1.7 \times 10^6$
events from a data sample corresponding to an integrated luminosity of 5.7
pb$^{-1}$ collected with the CMD-3 detector in the ...center-of-mass energy range
1010--1060 MeV. The cross section measured with an about 2\% systematic
uncertainty and it is used to calculate the contribution to the anomalous
magnetic moment of the muon $a_{\mu}^{K^+K^-} = (19.33 \pm 0.40) \times
10^{-10}$, and to obtain the $\phi(1020)$ meson parameters. We consider the
relationship between the $e^+e^- \to K^+K^-$ and $e^+e^- \to K^0_SK^0_L$ cross
sections and compare it to the theoretical expectations.
A cross section of the process $e^+e^- \to \pipi\pipi$ has been measured
using 6798$\pm$93 signal events from a data sample corresponding to an
integrated luminosity of 9.8 pb$^{-1}$ collected with ...the CMD-3 detector in the
center-of-mass energy range 920--1060 MeV. The measured cross section exhibits
an interference pattern of the $\phi(1020)\to\pipi\pipi$ decay with a
non-resonant process $e^+e^- \to \pipi\pipi$, from which we obtain the
branching fraction of the doubly suppressed decays (by G-parity and OZI rule):
$\BR(\phi\to\pipi\pipi) = (6.5\pm2.7\pm1.6)\times 10^{-6}$.
It’s good known the difference in 3.5 sigma between the muon (g – 2) experimental result and its calculation in Standard Model. To clarify this intriguing discrepancy the new stage of muon (g – 2) ...measurement is under preparation at Fermi National Laboratory. On other hand, regular data taking for measurements of hadron cross section production in e+ e− annihilations is under way since December 2010 at the electron-positron collider VEPP-2000 with the CMD-3 and SND detectors. The collected data sample corresponds to about 60 inverse picobarns of integrated luminosity per detector in the energy range from 0.32 up to 2 GeV. Preliminary analysis of various hadronic cross sections has been performed.
Regular data taking started at the VEPP-2000 e+e− collider with the CMD-3 detector. An energy scan of a center-of-mass energy range from 1 GeV to 2 GeV has been performed with an integrated ...luminosity of about 20 pb−1. We present first preliminary results from the CMD-3 detector.
The process $e^+e^- \to K^+K^-\pi^+\pi^-$ has been studied in the
center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23
pb$^{-1}$ collected with the CMD-3 detector at the ...VEPP-2000 $e^+e^-$ collider.
Using about 24000 selected events, the $e^+e^- \to K^+K^-\pi^+\pi^-$ cross
section has been measured with a systematic uncertainty decreasing from 11.7\%
at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of
$K^+K^-\pi^+\pi^-$ production dynamics has been performed.
The cross section of the process \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) is measured using the data collected with the CMD-\(3\) detector at the VEPP-\(2000\) collider in the center-of-mass ...energy range from \(1.1\) to \(2.0\) GeV. The decay mode \(\eta\rightarrow\gamma\gamma\) is used for \(\eta\) meson reconstruction in the data sample corresponding to an integrated luminosity of \(78.3\) pb\(^{-1}\). The energy dependence of the \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) cross section is fitted within the framework of vector meson dominance in order to extract the \(\Gamma(\rho(1450)\rightarrow{^{+}e^{-}})\mathcal{B}(\rho(1450)\rightarrow\eta\pi^{+}\pi^{-})\) and the \(\Gamma(\rho(1700)\rightarrow{e^{+}e^{-}})\mathcal{B}(\rho(1700)\rightarrow\eta\pi^{+}\pi^{-})\) products. Based on conservation of vector current, the analysed data are used to test the relationship between the \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) cross section and the spectral function in \(\tau^-\rightarrow\eta\pi^-\pi^0\nu_\tau\) decay. The \(e^{+}e^{-}\rightarrow\eta\pi^{+}\pi^{-}\) cross section measured with the CMD-\(3\) detector is in good agreement with the previous measurements.
The process \(e^+e^-{\to}K^+K^-\eta\) has been studied in the center-of-mass energy range from 1.59 to 2.007\,GeV using the data sample of 59.5 pb\(^{-1}\), collected with the CMD-3 detector at the ...VEPP-2000 \(e^+e^-\) collider in 2011, 2012 and 2017. The \(K^+K^-\eta\) final state is found to be dominated by the contribution of the \(\phi(1020)\eta\) intermediate state. The cross section of the process \(e^+e^-{\to}\phi(1020)\eta\) has been measured with a systematic uncertainty of 5.1\(\%\) on the base of 3009 \(\pm\) 67 selected events. The obtained cross section has been used to calculate the contribution to the anomalous magnetic moment of the muon: \(a_{\mu}^{\phi\eta}(E<1.8\, {\rm GeV})=(0.321 \pm 0.015_{\rm stat} \pm 0.016_{\rm syst}) \times 10^{-10}\), \(a_{\mu}^{\phi\eta}(E<2.0\, {\rm GeV})=(0.440 \pm 0.015_{\rm stat} \pm 0.022_{\rm syst}) \times 10^{-10}\). From the cross section approximation the \(\phi(1680)\) meson parameters have been determined with better statistical precision, than in previous studies.
Using a data sample of 6.8 pb$^{-1}$ collected with the CMD-3 detector at the
VEPP-2000 $e^+e^-$ collider we select about 2700 events of the $e^+e^- \to
p\bar{p}$ process and measure its cross ...section at 12 energy ponts with about
6\% systematic uncertainty. From the angular distribution of produced nucleons
we obtain the ratio $|G_{E}/G_{M}| = 1.49 \pm 0.23 \pm 0.30$.
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