The process $e^+e^- to pi^0gamma$ is studied with the SND detector at the VEPP-2000 $e^+e^-$ collider. Basing on data with an integrated luminosity of 41 pb$^{-1}$ recorded in 2010-2012 we measure the $e^+e^- to pi^0gamma$ cross section in the center-of-mass energy range from 1.075 up to 2 GeV. In the range 1.4-2.0 GeV the process $e^+e^- to pi^0gamma$ is studied for the first time.
We analyze a 37 pb$^{-1}$ data sample collected with the SND detector at the VEPP-2000 $e^+e^-$ collider in the center-of-mass energy range 1.05--2.00 GeV and present an updated measurement of the $e^+e^- to omega pi^0 to pi^0pi^0gamma$ cross section
. In particular, we correct the mistake in radiative correction calculation made in our previous measurement based on a part of the data. The measured cross section is fitted with the vector meson dominance model with three $rho$-like states and used to test the conserved vector current hypothesis in the $tau^-toomegapi^- u_{tau}$ decay.
The process $e^+e^- to pi^+pi^-pi^0eta$ is studied in the center-of-mass energy region below 2 GeV with the SND detector at the VEPP-2000 $e^+e^-$ collider. The four intermediate states contribute to this process: $omegaeta$, $phieta$, $a_0(980)rho$,
and a structureless $pi^+pi^-pi^0eta$ state. We measure the total $e^+e^- to pi^+pi^-pi^0eta$ cross section and the cross sections for its components: $omegaeta$, $phieta$, and a sum of $a_0(980)rho$ and the structureless state. Our results are in agreement with previous measurements and have comparable or better accuracies.
In the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider the cross section for the process $e^+e^-toetapi^+pi^-$ has been measured in the center-of-mass energy range from 1.22 to 2.00 GeV. Obtained results are in agreement with prev
ious measurements and have better accuracy. The energy dependence of the $e^+e^-toetapi^+pi^-$ cross section has been fitted with the vector-meson dominance model. From this fit the product of the branching fractions $B(rho(1450)toetapi^+pi^-)B(rho(1450)to e^+e^-)$ has been extracted and compared with the same products for $rho(1450)toomegapi^0$ and $rho(1450)topi^+pi^-$ decays. The obtained cross section data have been also used to test the conservation of vector current hypothesis.
The process $e^+e^-to K^+K^-pi^0$ is studied with the SND detector at the VEPP-2000 $e^+e^-$ collider. Basing on data with an integrated luminosity of 26.4~pb$^{-1}$ we measure the $e^+e^-to K^+K^-pi^0$ cross section in the center-of-mass energy rang
e from 1.28 up to 2 GeV. The measured mass spectrum of the $Kpi$ system indicates that the dominant mechanism of this reaction is the transition through the $K^{ast}(892)K$ intermediate state. The cross section for the $phipi^0$ intermediate state is measured separately. The SND results are consistent with previous measurements in the BABAR experiment and have comparable accuracy. We study the effect of the interference between the $phipi^0$ and $K^ast K$ amplitudes. It is found that the interference gives sizable contribution to the measured $e^+e^- to phi pi^0to K^+K^-pi^0$ cross section below 1.7 GeV.
The $e^+e^- to etapi^+pi^-$ cross section is measured at the SND detector in the $eta$ decay mode $etato 3pi^0$. The analysis is based on the data sample with an integrated luminosity of 32.7 pb$^{-1}$ collected at the VEPP-2000 $e^+e^-$ collider in
the center-of-mass energy range $sqrt{s}=1.075-2.000$ GeV. The data obtained in the $etato 3pi^0$ decay mode are found to be in agreement with the previous SND measurements in the $etato gammagamma$ mode. Therefore the measurements in the two modes are combined.
M. N. Achasov
,A. Yu. Barnyakov
,K. I. Beloborodov
.
(2018)
.
"Measurement of the $e^+e^- to pi^0gamma$ cross section in the energy range 1.075--2 GeV at SND"
.
Vladimir Druzhinin
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