Contribution to muon<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>g</mml:mi><mml:mi>−</mml:mi><mml:mn>2</mml:mn></mml:math>from<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mi>γ</mml:mi></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>η</mml:mi><mml:mi>γ</mml:mi></mml:math>i

Achasov, N. N.; Киселев, А. В.

doi:10.1103/physrevd.65.097302

Cited by 42 publications

(74 citation statements)

References 4 publications

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“…which follows from expressions (8)(9)(10). The e + e − → ωπ 0 cross section was obtained from SND measurements of the e + e − → ωπ 0 → π 0 π 0 γ cross section 26 :…”

Section: Cross Section Measurementmentioning

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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“…which follows from expressions (8)(9)(10). The e + e − → ωπ 0 cross section was obtained from SND measurements of the e + e − → ωπ 0 → π 0 π 0 γ cross section 26 :…”

Section: Cross Section Measurementmentioning

confidence: 99%

Study of the processe+e−→π+π

et al. 2002

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“…Since the electromagnetic current couples to π 0 γ via ω meson exchange, the low-energy cross section can be improved by assuming the ω-meson dominance [113], which gives…”

Section: Combining Data Setsmentioning

confidence: 99%

“…µ the form of the kernel can be found in [113], and is used to evaluate the small π 0 γ contribution to a had,LO µ . Dispersion relation (5), evaluated at s = M 2 Z , may be written in the form…”

Section: Combining Data Setsmentioning

confidence: 99%

Predictions forg−2of the muon andαQED(MZ
Hagiwara
¹
,
Martin
²
,
Nomura
³

et al. 2004
Phys. Rev. D
285
25
397
2
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Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractWe calculate (g − 2) of the muon and the QED coupling α(M 2 Z ), by improving the determination of the hadronic vacuum polarization contributions and their uncertainties. We include the recently re-analysed CMD-2 data on e + e − → π + π − . We carefully combine a wide variety of data for the e + e − production of hadrons, and obtain the optimum form of R(s) ≡ σ 0 had (s)/σ pt (s), together with its uncertainty. Our results for the hadronic contributions to g − 2 of the muon are a had,LO µ = (692.4 ± 5.9 exp ± 2.4 rad ) × 10 −10 and a had,NLO µ = (−9.8 ± 0.1 exp ± 0.0 rad ) × 10 −10 , and for the QED coupling ∆α (5) had (M 2 Z ) = (275.5± 1.9 exp ± 1.3 rad )× 10 −4 . These yield (g − 2)/2 = 0.00116591763(74), which is about 2.4σ below the present world average measurement, and α(M 2 Z ) −1 = 128.954 ± 0.031. We compare our (g − 2) value with other predictions and, in particular, make a detailed comparison with the latest determination of (g − 2) by Davier et al.

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“…The form of K for s < 4m 2 µ is given in [17], and is used to evaluate the small π 0 γ contribution to a had,LO µ . To evaluate σ had (s), we use experimental data up to 11.09 GeV and perturbative QCD thereafter.…”

Section: Introductionmentioning

confidence: 99%

The SM prediction of g−2 of the muon

et al. 2003

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractWe calculate (g − 2)/2 of the muon, by improving the determination of the hadronic vacuum polarisation contribution, a had,LO µ , and its uncertainties. The different e + e − data sets for each exclusive (and the inclusive) channel are combined in order to obtain the optimum estimate of the cross sections and their uncertainties. QCD sum rules are evaluated in order to resolve an apparent discrepancy between the inclusive data and the sum of the exclusive channels. We conclude a had,LO µ = (683.1 ± 5.9 exp ± 2.0 rad ) × 10 −10 which, when combined with the other contributions to (g − 2)/2, is about 3σ below the present world average measurement.

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Contribution to muong−2fromπ0γandηγi

Cited by 42 publications

References 4 publications

Study of the processe+e−→π+π

Study of the processe+e−→π+π

Predictions forg−2of the muon andαQED(MZ
Hagiwara
¹
,
Martin
²
,
Nomura
³

et al. 2004
Phys. Rev. D
285
25
397
2
View full text Add to dashboard Cite

The SM prediction of g−2 of the muon

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Contribution to muong−2fromπ0γandηγi

Cited by 42 publications

References 4 publications

Study of the processe+e−→π+π

Study of the processe+e−→π+π

Predictions forg−2of the muon andαQED(MZHagiwara1, Martin2, Nomura3 et al. 2004Phys. Rev. D285253972View full textAdd to dashboardCite

The SM prediction of g−2 of the muon

Contact Info

Product

Resources

About

Predictions forg−2of the muon andαQED(MZ
Hagiwara
¹
,
Martin
²
,
Nomura
³

et al. 2004
Phys. Rev. D
285
25
397
2
View full text Add to dashboard Cite