The process
e
+
e
-
→
η
η
γ
is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb
-
1
collected by the SND detector at the VEPP-2000
e
+
e
-
...collider. The
e
+
e
-
→
η
η
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
ϕ
η
intermediate state. Our result on the
e
+
e
-
→
η
η
γ
cross section is consistent with the
e
+
e
-
→
ϕ
η
measurement in the
ϕ
→
K
+
K
-
mode. The search for radiative processes contributing to the
e
+
e
-
→
η
η
γ
cross section is performed, and no significant signal is observed.
Abstract The process $$e^+e^-\rightarrow \eta \eta \gamma $$ e + e - → η η γ is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb $$^{-1}$$ - ...1 collected by the SND detector at the VEPP-2000 $$e^+e^-$$ e + e - collider. The $$e^+e^-\rightarrow \eta \eta \gamma $$ e + e - → η η γ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $$\phi \eta $$ ϕ η intermediate state. Our result on the $$e^+e^-\rightarrow \eta \eta \gamma $$ e + e - → η η γ cross section is consistent with the $$e^+e^-\rightarrow \phi \eta $$ e + e - → ϕ η measurement in the $$\phi \rightarrow K^+ K^-$$ ϕ → K + K - mode. The search for radiative processes contributing to the $$e^+e^-\rightarrow \eta \eta \gamma $$ e + e - → η η γ cross section is performed, and no significant signal is observed.
Abstract
The process
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
is studied in the center-of-mass energy range 1.17–2.00 GeV using data with an integrated luminosity of 201 pb
$$^{-1}$$
-
...1
collected by the SND detector at the VEPP-2000
$$e^+e^-$$
e
+
e
-
collider. The
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
$$\phi \eta $$
ϕ
η
intermediate state. Our result on the
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
cross section is consistent with the
$$e^+e^-\rightarrow \phi \eta $$
e
+
e
-
→
ϕ
η
measurement in the
$$\phi \rightarrow K^+ K^-$$
ϕ
→
K
+
K
-
mode. The search for radiative processes contributing to the
$$e^+e^-\rightarrow \eta \eta \gamma $$
e
+
e
-
→
η
η
γ
cross section is performed, and no significant signal is observed.
The VEPP-2000 electron–positron collider has been operating at the Budker Institute of Nuclear Physics (BINP) since 2010. Applying the concept of round colliding beams allowed the record value of the ...beam–beam parameter ξ ∼ 0.12 to be reached. The upgrading of the VEPP-2000 complex, including the connection to the new BINP Injection Complex and modification of the electron–position booster and the BEP–VEPP-2000 transfer channels to work at 1 GeV, resulted in a significant increase in luminosity. Work on statistical data collection using detectors is in progress.
Abstract The process $$e^+e^-\rightarrow \eta \pi ^0\gamma $$ e + e - → η π 0 γ is studied in the center-of-mass energy range 1.05–2.00 GeV using data with an integrated luminosity of 94.5 $$\hbox ...{pb}^{-1}$$ pb - 1 collected by the SND detector at the VEPP-2000 $$e^{+}e^{-}$$ e + e - collider. The $$e^+e^-\rightarrow \eta \pi ^0\gamma $$ e + e - → η π 0 γ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the $$\omega \eta $$ ω η intermediate state. The measured cross section of the subprocess $$e^+e^-\rightarrow \omega \eta \rightarrow \eta \pi ^0\gamma $$ e + e - → ω η → η π 0 γ is consistent with previous measurements in the $$e^+e^-\rightarrow \pi ^+\pi ^-\pi ^0\eta $$ e + e - → π + π - π 0 η mode. It is found, with a significance of $$5.6\sigma $$ 5.6 σ , that the process $$e^+e^-\rightarrow \eta \pi ^0\gamma $$ e + e - → η π 0 γ is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g. $$e^+e^-\rightarrow a_{0}(1450)\gamma $$ e + e - → a 0 ( 1450 ) γ , is measured. It is found to be 15–20 pb in the wide energy range from 1.3 to 1.9 GeV.
The process e+e-→ηπ0γ is studied in the center-of-mass energy range 1.05–2.00 GeV using data with an integrated luminosity of 94.5 pb-1 collected by the SND detector at the VEPP-2000 e+e- collider. ...The e+e-→ηπ0γ cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the ωη intermediate state. The measured cross section of the subprocess e+e-→ωη→ηπ0γ is consistent with previous measurements in the e+e-→π+π-π0η mode. It is found, with a significance of 5.6σ, that the process e+e-→ηπ0γ is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g. e+e-→a0(1450)γ, is measured. It is found to be 15–20 pb in the wide energy range from 1.3 to 1.9 GeV.
Abstract
The process
$$e^+e^-\rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
η
π
0
γ
is studied in the center-of-mass energy range 1.05–2.00 GeV using data with an integrated luminosity of 94.5
$$\hbox ...{pb}^{-1}$$
pb
-
1
collected by the SND detector at the VEPP-2000
$$e^{+}e^{-}$$
e
+
e
-
collider. The
$$e^+e^-\rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
η
π
0
γ
cross section is measured for the first time. It is shown that the dominant mechanism of this reaction is the transition through the
$$\omega \eta $$
ω
η
intermediate state. The measured cross section of the subprocess
$$e^+e^-\rightarrow \omega \eta \rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
ω
η
→
η
π
0
γ
is consistent with previous measurements in the
$$e^+e^-\rightarrow \pi ^+\pi ^-\pi ^0\eta $$
e
+
e
-
→
π
+
π
-
π
0
η
mode. It is found, with a significance of
$$5.6\sigma $$
5.6
σ
, that the process
$$e^+e^-\rightarrow \eta \pi ^0\gamma $$
e
+
e
-
→
η
π
0
γ
is not completely described by hadronic vector-pseudoscalar intermediate states. The cross section of this missing contribution, which can originate from radiation processes, e. g.
$$e^+e^-\rightarrow a_{0}(1450)\gamma $$
e
+
e
-
→
a
0
(
1450
)
γ
, is measured. It is found to be 15–20 pb in the wide energy range from 1.3 to 1.9 GeV.
Abstract The dynamics of the process $$ e^+e^- \rightarrow \pi ^+\pi ^-\pi ^0 $$ e + e - → π + π - π 0 is studied in the energy region from 1.15 to 2.00 GeV using data accumulated with the SND ...detector at the VEPP-2000 $$e^+e^-$$ e + e - collider. The Dalitz plot distribution and $$\pi ^+\pi ^-$$ π + π - mass spectrum are analyzed in a model including the intermediate states $$\rho (770)\pi $$ ρ ( 770 ) π , $$\rho (1450)\pi $$ ρ ( 1450 ) π , and $$\omega \pi ^0$$ ω π 0 . As a result, the energy dependences of the $$\rho (770)\pi $$ ρ ( 770 ) π and $$\rho (1450)\pi $$ ρ ( 1450 ) π cross sections and the relative phases between the $$\rho (770)\pi $$ ρ ( 770 ) π amplitude and the $$\rho (1450)\pi $$ ρ ( 1450 ) π and $$\omega \pi ^0$$ ω π 0 amplitudes are obtained. The $$\rho (1450)\pi $$ ρ ( 1450 ) π cross section has a peak in the energy region of the $$\omega (1650)$$ ω ( 1650 ) resonance (1.55–1.75 GeV). In this energy range the contributions of the $$\rho (770)\pi $$ ρ ( 770 ) π and $$\rho (1450)\pi $$ ρ ( 1450 ) π states are of the same order of magnitude. No resonance structure near 1.65 GeV is observed in the $$\rho (770)\pi $$ ρ ( 770 ) π cross section. We conclude that the intermediate state $$\rho (1450)\pi $$ ρ ( 1450 ) π gives a significant contribution to the decay of $$\omega (1650)\rightarrow \pi ^+\pi ^-\pi ^0$$ ω ( 1650 ) → π + π - π 0 , whereas the $$\rho (770)\pi $$ ρ ( 770 ) π mechanism dominates in the decay $$\omega (1420)\rightarrow \pi ^+\pi ^-\pi ^0$$ ω ( 1420 ) → π + π - π 0 .
The dynamics of the process e+e-→π+π-π0 is studied in the energy region from 1.15 to 2.00 GeV using data accumulated with the SND detector at the VEPP-2000 e+e- collider. The Dalitz plot distribution ...and π+π- mass spectrum are analyzed in a model including the intermediate states ρ(770)π, ρ(1450)π, and ωπ0. As a result, the energy dependences of the ρ(770)π and ρ(1450)π cross sections and the relative phases between the ρ(770)π amplitude and the ρ(1450)π and ωπ0 amplitudes are obtained. The ρ(1450)π cross section has a peak in the energy region of the ω(1650) resonance (1.55–1.75 GeV). In this energy range the contributions of the ρ(770)π and ρ(1450)π states are of the same order of magnitude. No resonance structure near 1.65 GeV is observed in the ρ(770)π cross section. We conclude that the intermediate state ρ(1450)π gives a significant contribution to the decay of ω(1650)→π+π-π0, whereas the ρ(770)π mechanism dominates in the decay ω(1420)→π+π-π0.
Abstract The dynamics of the process $$ e^+e^- \rightarrow \pi ^+\pi ^-\pi ^0 $$ e + e - → π + π - π 0 is studied in the energy region from 1.15 to 2.00 GeV using data accumulated with the SND ...detector at the VEPP-2000 $$e^+e^-$$ e + e - collider. The Dalitz plot distribution and $$\pi ^+\pi ^-$$ π + π - mass spectrum are analyzed in a model including the intermediate states $$\rho (770)\pi $$ ρ ( 770 ) π , $$\rho (1450)\pi $$ ρ ( 1450 ) π , and $$\omega \pi ^0$$ ω π 0 . As a result, the energy dependences of the $$\rho (770)\pi $$ ρ ( 770 ) π and $$\rho (1450)\pi $$ ρ ( 1450 ) π cross sections and the relative phases between the $$\rho (770)\pi $$ ρ ( 770 ) π amplitude and the $$\rho (1450)\pi $$ ρ ( 1450 ) π and $$\omega \pi ^0$$ ω π 0 amplitudes are obtained. The $$\rho (1450)\pi $$ ρ ( 1450 ) π cross section has a peak in the energy region of the $$\omega (1650)$$ ω ( 1650 ) resonance (1.55–1.75 GeV). In this energy range the contributions of the $$\rho (770)\pi $$ ρ ( 770 ) π and $$\rho (1450)\pi $$ ρ ( 1450 ) π states are of the same order of magnitude. No resonance structure near 1.65 GeV is observed in the $$\rho (770)\pi $$ ρ ( 770 ) π cross section. We conclude that the intermediate state $$\rho (1450)\pi $$ ρ ( 1450 ) π gives a significant contribution to the decay of $$\omega (1650)\rightarrow \pi ^+\pi ^-\pi ^0$$ ω ( 1650 ) → π + π - π 0 , whereas the $$\rho (770)\pi $$ ρ ( 770 ) π mechanism dominates in the decay $$\omega (1420)\rightarrow \pi ^+\pi ^-\pi ^0$$ ω ( 1420 ) → π + π - π 0 .
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