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A. V. Vasiljev

Publications and source records attributed to A. V. Vasiljev.

At least 19 recordsLinked to original sources
arXiv2019

Measurement of the $e^+e^- \to π^+π^-π^0η$ cross section below $\sqrt{s}=2$ GeV

The process $e^+e^- \to π^+π^-π^0η$ 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: $ωη$, $ϕη$, $a_0(980)ρ$, and a structureless $π^+π^-π^0η$ state. We measure the total $e^+e^- \to π^+π^-π^0η$ cross section and the cross sections for its components: $ωη$, $ϕη$, and a sum of $a_0(980)ρ$ and the structureless state. Our results are in agreement with previous measurements and have comparable or better accuracies.

hep-ex↗
arXiv2018

Measurement of the $e^+e^- \to π^0γ$ cross section in the energy range 1.075--2 GeV at SND

The process $e^+e^- \to π^0γ$ 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 $e^+e^- \to π^0γ$ 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 $e^+e^- \to π^0γ$ is studied for the first time.

hep-ex↗
arXiv2018

Search for the process $\mathbf{e^+e^- \toη}$

A search for the rare decay $η\rightarrow e^+e^-$ is performed using the inverse process $e^+e^- \rightarrow η$ in the decay mode $η\toπ^0π^0π^0 $. We analyze data with an integrated luminosity of 654 nb$^{-1} $ accumulated at the VEPP-2000 $e^+e^-$ collider with the SND detector at the center-of-mass energy $E=m_ηc ^2\approx 548 $ MeV, and set the upper limit $ {\cal B} (η\rightarrow e^+ e^-) < 7 \times 10^{-7} $ at the 90\% confidence level.

hep-ex↗
arXiv2017

Measurement of the $e^+e^- \to ηπ^+π^-$ cross section with the SND detector at the VEPP-2000 collider

The $e^+e^- \to ηπ^+π^-$ cross section is measured at the SND detector in the $η$ decay mode $η\to 3π^0$. 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 $η\to 3π^0$ decay mode are found to be in agreement with the previous SND measurements in the $η\to γγ$ mode. Therefore the measurements in the two modes are combined.

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arXiv2016

Updated measurement of the $e^+e^- \to ωπ^0 \to π^0π^0γ$ cross section with the SND detector

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 $e^+e^- \to ωπ^0 \to π^0π^0γ$ 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 $ρ$-like states and used to test the conserved vector current hypothesis in the $τ^-\toωπ^-ν_τ$ decay.

hep-ex↗
arXiv2016

Measurement of the $\mathbf{e^+e^-\to K^+K^-}$ cross section in the energy range $\mathbf{\sqrt{s}=1.05-2.0}$ GeV

The $e^+e^-\to K^+K^-$ cross section is measured in the center-of-mass energy range $1.05-2.00$ GeV at the SND detector. The measurement is based on data with an integrated luminosity of 35 pb$^{-1}$ collected at the VEPP-2000 $e^+e^-$-collider. The obtained results are consistent with the previous most accurate data obtained in the BABAR experiment and have a comparable accuracy.

hep-ex↗
arXiv2016

Study of the process $e^+e^-\toωηπ^0$ in the energy range $\sqrt{s} <2$ GeV with the SND detector

The process $e^+e^-\toωηπ^0$ is studied in the energy range $1.45-2.00$ GeV using data with an integrated luminosity of 33 pb$^{-1}$ accumulated by the SND detector at the $e^+e^-$ collider VEPP-2000. The $e^+e^-\toωηπ^0$ cross section is measured for the first time. The cross section has a threshold near 1.75 GeV. Its value is about 2 nb in the energy range $1.8-2.0$ GeV. The dominant intermediate state for the process $e^+e^- \to ωηπ^0$ is found to be $ωa_0(980)$.

hep-ex↗
arXiv2016

Measurement of the $e^+e^- \to ωη$ cross section below $\sqrt{s}=2$ GeV

The cross section for the process $e^+e^- \to ωη$ is measured in the center-of-mass energy range 1.34--2.00 GeV. The analysis is based on data collected with the SND detector at the VEPP-2000 $e^+e^-$ collider. The measured $e^+e^- \to ωη$ cross section is the most accurate to date. A significant discrepancy is observed between our data and previous BABAR measurement.

hep-ex↗
arXiv2016

Study of the reaction $e^+e^- \to π^0γ$ with the SND detector at the VEPP-2M collider

The process $e^+e^- \to π^0γ$ has been studied in the experiment with the SND detector at the VEPP-2M $e^+e^-$ collider. The $e^+e^- \to π^0γ$ cross section has been measured in the center-of-mass energy range from 0.60 to 1.38 GeV. The cross section is well described by the vector meson dominance model. From the fit to the cross section data we have determined the branching fractions $B(ρ\toπ^0γ)=(4.20\pm0.52)\times10^{-4}$, $B(ω\toπ^0γ)=(8.88\pm0.18)\%$, $B(ϕ\toπ^0γ)=(1.367\pm0.072)\times10^{-3}$, and the relative phase between the $ρ$ and $ω$ amplitudes $φ_ρ=(-12.7\pm4.5)^\circ$. Our data on the process $e^+e^- \to π^0γ$ are the most accurate to date.

hep-ex↗
arXiv2015

Measurement of the $K_L$ nuclear interaction length in the NaI(Tl) calorimeter

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.

hep-ex↗
arXiv2015

On a search for the $η\rightarrow e^+ e^-$ decay at the VEPP-2000 $e^+e^-$ collider

A sensitivity of the VEPP-2000 $e^+e^-$ collider in a search for the rare decay $η\rightarrow e^+ e^-$ has been studied. The inverse reaction $e^+ e^- \rightarrow η$ is proposed for this search. We have analyzed a data sample with an integrated luminosity of 108 nb$^{-1}$ collected with the SND detector in the center-of-mass energy range 520-580 MeV and found no background events for the reaction $e^+ e^- \rightarrow η$ in the decay mode $η\toπ^0π^0π^0$. In the absence of background, a sensitivity to ${\cal B}(η\rightarrow e^+ e^-)$ of $10^{-6}$ can be reached during two weeks of VEPP-2000 operation. Such a sensitivity is better than the current upper limit on ${\cal B}(η\rightarrow e^+ e^-)$ by a factor of 2.3.

hep-ex↗
arXiv2015

Search for the $η^{\prime}\to e^+e^-$ decay with the SND detector

A search for the process $e^+e^- \to η^\prime$ has been performed with the SND detector at the VEPP-2000 $e^+e^-$ collider. The data were accumulated at the center-of-mass energy of $957.78\pm 0.06$ MeV with an integrated luminosity of about 2.9 pb$^{-1}$. For reconstruction of the $η^\prime$ meson five decay chains have been used: $η^{\prime}\toηπ^+π^-$ followed by the $η$ decays to $γγ$ and $3π^0 $, and $η^{\prime} \to ηπ^0π^0$ followed by the $η$ decays to $π^+π^-π^0$, $γγ$, and $3π^0$. As a result, the upper limit has been set on the $η^\prime$ electronic width: $Γ_{η^{\prime}\to e^+e^-} < 0.0020$ eV at the 90\% confidence level.

hep-ex↗
arXiv2015

Measurement of the $e^+e^- \to ηπ^+π^-$ cross section in the center-of-mass energy range 1.22--2.00 GeV with the SND detector at the VEPP-2000 collider

In the experiment with the SND detector at the VEPP-2000 $e^+e^-$ collider the cross section for the process $e^+e^-\toηπ^+π^-$ 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 $e^+e^-\toηπ^+π^-$ cross section has been fitted with the vector-meson dominance model. From this fit the product of the branching fractions $B(ρ(1450)\toηπ^+π^-)B(ρ(1450)\to e^+e^-)$ has been extracted and compared with the same products for $ρ(1450)\toωπ^0$ and $ρ(1450)\toπ^+π^-$ decays. The obtained cross section data have been also used to test the conservation of vector current hypothesis.

hep-ex↗
arXiv2013

Study of the process $e^+e^-\toηγ$ in the center-of-mass energy range 1.07--2.00 GeV

The $e^+e^-\toηγ$ cross section has been measured in the center-of-mass energy range 1.07--2.00 GeV using the decay mode $η\to 3π^0$, $π^0\to γγ$. The analysis is based on 36 pb$^{-1}$ of integrated luminosity collected with the SND detector at the VEPP-2000 $e^+e^-$ collider. The measured cross section of about 35 pb at 1.5 GeV is explained by decays of the $ρ(1450)$ and $ϕ(1680)$ resonances.

hep-ex↗
arXiv2013

Study of e+e- --> omega pi0 --> pi0 pi0 gamma in the energy range 1.05--2.00 GeV with SND

The cross section for the process e+e- --> omega pi0 --> pi0 pi0 gamma has been measured in the energy range 1.05--2.00 GeV. The experiment has been performed at the e+e- collider VEPP-2000 with the SND detector. The measured e+e- --> omega pi0 cross section above 1.4 GeV is the most accurate to date. Below 1.4 GeV our data are in good agreement with the previous SND and CMD-2 measurements. Data on the e+e- --> omega pi0 cross section are well described by the VMD model with two excited rho-like states. From the measured cross section we have extracted the gamma^* --> omega pi0 transition form factor. It has been found that the VDM model cannot describe simultaneously our data and data obtained from the omega --> pi0 mu+ mu- decay. We have also tested CVC hypothesis comparing our results on the e+e- --> omega pi0 cross section with data on the tau- --> omega pi- nu_{tau} decay.

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