Study of (π+π -π+π-) and (π+π-π0) channel in e+e- annihilation at (1.450÷1.875) GeV cm. energy

Esposito, B.; Marini, A.; Ronga, F. J.; Patterí, P.; Nigro, M.; Pescara, L.; Bernabei, R.; Angelo, S. d’; Monacelli, P.; Moricca, M.; Paoluzi, L.; Santonico, R.; Sebastiani, Federico

doi:10.1007/bf02770196

Cited by 22 publications

(3 citation statements)

References 11 publications

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“…-The e + e − → π + π − π + π − final state was studied by the experiments OLYA [39], ND [34], MEA [44], CMD [45], DM1 [46,47], DM2 [40,42,43] and M3N [36]. The corresponding spectral function from τ − → π − 3π 0 ν τ (according to Eq.…”

Section: The Origin Of the Datamentioning

confidence: 99%

Improved determination of the hadronic contribution to the muon (

Alemany¹,

Davier²,

Höcker³

1998

Eur. Phys. J. C

152

280

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We have reevaluated the hadronic contribution to the anomalous magnetic moment of the muon (g − 2) and to the running of the QED fine structure constant α(s) at s = M 2 Z . We incorporated new data from hadronic τ decays, recently published by the ALEPH Collaboration. In addition, compared to previous analyses, we use more extensive e + e − annihilation data sets. The integration over the total hadronic cross section is performed using experimental data up to 40 GeV and results from perturbative QCD above 40 GeV. The improvement from τ data concerns mainly the pion form factor, where the uncertainty in the corresponding integral could be reduced by more than a factor of two. We obtain for the lowest order hadronic vacuum polarization graph a had µ = (695.0 ± 15.0)×10 −10 and ∆α (5) had (M 2 Z ) = (280.9 ± 6.3)×10 −4 using e + e − data only. The corresponding results for combined e + e − and τ data are a had µ = (701.1 ± 9.4)×10 −10 and ∆α (5) had (M 2 Z ) = (281.7 ± 6.2) ×10 −4 , where the latter is calculated using the contribution from the five lightest quarks.

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Section: The Origin Of the Datamentioning

confidence: 99%

Improved determination of the hadronic contribution to the muon (

Alemany¹,

Davier²,

Höcker³

1998

Eur. Phys. J. C

152

280

View full text Add to dashboard Cite

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“…The e + e − → π + π − π 0 cross section in the energy region above φ meson and up to 2200 MeV has been studied in several experiments [11][12][13][14][15][16] , but none of them have covered the whole region. The SND study of this cross section in the range √ s = 1040 -1380 MeV based on a part of collected data was already reported in Ref.…”

Section: Introductionmentioning

confidence: 99%

Study of the processe+e−→π+π

et al. 2002

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Study of the process e + e − → π + π − π 0 in the energy region √ s from 0.98 to 1.38 GeV. The cross section of the process e + e − → π + π − π 0 was measured in the Spherical Neutral Detector experiment at the VEPP-2M collider in the energy region √ s = 980 ÷ 1380 MeV. The measured cross section, together with the e + e − → π + π − π 0 and ωπ + π − cross sections obtained in other experiments, was analyzed in the framework of the generalized vector meson dominance model. It was found that the experimental data can be described by a sum of ω, φ mesons and two ω ′ and ω ′′ resonances contributions, with masses m ω ′ ∼ 1490, m ω ′′ ∼ 1790 MeV and widths Γ ω ′ ∼ 1210, Γ ω ′′ ∼ 560 MeV. The analysis of the π + π − invariant mass spectra in the energy region √ s from 1100 to 1380 MeV has shown that for their description one should take into account the e + e − → ωπ 0 → π + π − π 0 mechanism also. The phase between the amplitudes corresponding to the e + e − → ωπ and e + e − → ρπ intermediate states was measured for the first time. The value of the phase is close to zero and depends on energy. I. INTRODUCTIONThe cross section of hadron production in the e + e − annihilation in the energy region √ s < 1.03 GeV can be described within the vector meson dominance model (VDM) framework and is determined by the transitions of light vector mesons (ρ, ω, φ) into the final states. The light vector mesons have been studied rather well. They are quark-antiquark qq (q = u, d, s) bound states, and their masses, widths and main decays have been measured with high accuracy 1 . The cross section for hadron production above the φ(1020) resonance ( √ s ≃ 1.03-2 GeV) cannot be described in the conventional VDM framework (taking into account ρ, ω and φ mesons only) indicating the existence of states with vector meson quantum numbers I G (J P C ) = 1 + (1 −− ), 0 − (1 −− ) and with masses of about 1450, 1650 MeV. Parameters of these states are not well established due to inaccurate and conflicting experimental data. The nature of these states is not clear either. In some reviews of experimental data they are considered as a mixture of qq with 4-quark qqqq and hybrid qqg states 2-5 . On the other hand, the experimental data do not contradict *

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“…The relative contributions of the mentioned processes can't be obtained without the detailed analysis of the process dynamics. Some information on the process e + e − → 4π has been obtained in [2][3][4][5][6][7][8], where the investigation of e + e − annihilation into hadrons was restricted by measurements of the cross sections only. However, the abundance of various possible mechanisms and their complicated interference results in the necessity of simultaneous analysis of two possible final states (2π + 2π − and π + π − 2π 0 ) which requires a general purpose detector capable of measuring energies and angles of both charged and neutral particles.…”

Section: Introductionmentioning

confidence: 99%