Measurement of the reaction e+e−→ηπ+π− in the center of mass energy interval 1350–2400 MeV

Antonelli, A.; Baldini, R.; Calcaterra, S.; Capon, G.; Schioppa, M.; Augustin, J. E.; Ayach, L.; Cosme, G.; Couchot, F.; Dudelzak, B.; Fulda, F.; Grosdidier, G.; Jean‐Marie, B.; Jullian, S.; Lalanne, D.; Lepeltier, V.; Mané, F.; Paulot, C.; Riskalla, R.; Roy, P.; Szklarz, G.; Ajaltouni, Z.; Falvard, A.; Jousset, J.; Michel, B.; Montret, J. C.; Bisello, D.; Busetto, G.; Pescara, L.; Sartori, P.; Stančo, L.

doi:10.1016/0370-2693(88)91250-6

Cited by 67 publications

(36 citation statements)

References 20 publications

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“…the left slope of the ρ′ meson only, we can not determine its parameters. However, one can obtain the e + e − → ηγ cross section in the much broader energy range 1300 to 2450 MeV from the measurements of the cross section e + e − → ηπ + π − by DM2 [22] and CMD-2 [16] using (9). If the cross sections obtained in such a way are combined with the cross section e + e − → ηγ from our measurement and a fit is performed with a free mass and width of the ρ′ meson, then reasonable description of the whole data is achieved with the following values of resonance parameters: Table 3 as well as those in (10) shows that the model dependence of the branching ratios does not exceed 5% for the ρ and ω mesons whereas for the φ → ηγ decay it is less than 1%.…”

Section: Discussionmentioning

confidence: 99%

Study of the process e+e−→ηγ in c.m. energy range 600–1380 MeV at CMD-2

et al. 2001

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The cross section of the process e + e − → ηγ has been measured in the 600-1380 MeV c.m. energy range with the CMD-2 detector. The following branching ratios have been determined: B(ρ → ηγ) = (3.28 ± 0.37 ± 0.23) · 10 −4 , B(ω → ηγ) = (5.10 ± 0.72 ± 0.34) · 10 −4 , B(φ → ηγ) = (1.287 ± 0.013 ± 0.063) · 10 −2 .Evidence for the ρ(1450) → ηγ decay has been obtained for the first time.

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Section: Discussionmentioning

confidence: 99%

Study of the process e+e−→ηγ in c.m. energy range 600–1380 MeV at CMD-2

et al. 2001

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“…In this approximation the fact that with the free magnitudes and phases of all four ρ, ω, φ, and ρ ′ resonances, the minimized likelihood function has several minima and thus, a choice of the right minimization solution is ambiguous, was ignored. Additional physical restrictions must be applied to, at least, the parameters of the ρ ′ resonance, in order to make a right choice of the minimization solution.In this work the ρ ′ -meson parameters were estimated from the experimental data on the e + e − → ηρ cross section [2,3]. The cross section value in the ρ ′ -resonance maximum obtained from the approximation of the e + e − → ηρ cross section can be translated to the e + e − → ρ ′ → ηγ cross section using VDM as in Ref.…”

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confidence: 99%

“…In this work the ρ ′ -meson parameters were estimated from the experimental data on the e + e − → ηρ cross section [2,3]. The cross section value in the ρ ′ -resonance maximum obtained from the approximation of the e + e − → ηρ cross section can be translated to the e + e − → ρ ′ → ηγ cross section using VDM as in Ref.…”

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confidence: 99%

Reanalysis of thee+e−→ηγreaction cross section

et al. 2007

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In the experiment with the SND detector at the VEPP-2M e + e − collider measuring the e + e − → ηγ cross section in the energy range 0.6 < √ s < 1.38 GeV the reanalysis of data is performed. The goal is to improve the accuracy of the previous results by analysing ambiguities in the approximation of energy dependence of the e + e − → ηγ cross section, which were not taken into account in our previous study. We report new results on the approximation of the e + e − → ηγ cross section based on Vector Dominance Model under new model parameter assumptions. In our previous work [1] we performed a measurement of the e + e − → ηγ reaction cross section for two η-meson decay modes: η → 3π 0 and η → π + π − π 0 . The measured cross section was approximated within Vector Dominance Model (VDM). In this approximation the fact that with the free magnitudes and phases of all four ρ, ω, φ, and ρ ′ resonances, the minimized likelihood function has several minima and thus, a choice of the right minimization solution is ambiguous, was ignored. Additional physical restrictions must be applied to, at least, the parameters of the ρ ′ resonance, in order to make a right choice of the minimization solution.In this work the ρ ′ -meson parameters were estimated from the experimental data on the e + e − → ηρ cross section [2,3]. The cross section value in the ρ ′ -resonance maximum obtained from the approximation of the e + e − → ηρ cross section can be translated to the e + e − → ρ ′ → ηγ cross section using VDM as in Ref. [4]. The approximation of the data on the e + e − → ηρ cross section was done with three different models describing the energy dependence of the ρ ′ resonance width:Under these assumptions the resulting mass, width, and maximum cross section of the ρ ′ resonance varied within 1440-1520 MeV, 220-400 MeV, and 0.08-0.13 nb, respectively. All three ρ ′ parameter sets were used in the e + e − → ηγ cross section approximation. The difference in the experimental results was included in the systematic uncertainty of the final result. The cross section at the ρ ′ resonance maximum acquired an additional 20% systematic error from the uncertainty of the cross section calculation in the VDM.Natural values for the phase of the ρ ′ amplitude are 0 or 180 degrees. The phase shift from these values can be induced by the ρ and ρ ′ mixing via common decay channels, for example, ρ, ρ ′ → ωπ 0 . In the model considered in Ref. [5] it was shown that mixing is strongly energy dependent. For the approximation of the data on e + e − → ηγ cross section the ϕ ρ ′ value at the φ resonance maximum is important. Since at this energy the ρ − ρ ′ mixing is small, no significant phase shifts from 0 or 180 degrees are expected. Two approximations with the ϕ ρ ′ phase fixed at these values were considered. In order to estimate a corresponding systematic uncertainty of the approximation parameters due to the ρ ′ phase uncertainty, we varied ϕ ρ ′ by ±20 • with respect to its initial values.The fitting results with the ρ ′ parameters fixed to described ...

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“…Also data on e + e − → π + π − η can be used to test the conservation of the vector current (CVC) hypothesis. The reaction (1) was first observed at the end of 70's in the DM1 experiment [1] and since that time it was studied by Orsay [2], Novosibirsk [3][4][5][6] groups and by the BaBar collaboration [7,8]. From a theoretical point of view the ηππ production in the e + e − -annihilation and τ-lepton decay was discussed in [4,[9][10][11] using different approaches.…”

Section: Introductionmentioning

confidence: 99%

“…Three theoretical models have been applied to study the process (1) and they are shortly described below. The corresponding cross section can be written as [5] σ(s) = 4α 2 3…”

Section: Introductionmentioning

confidence: 99%