Update: A reanalysis of hadronic cross section measurements at CMD-2

Akhmetshin, R.R.; Anashkin, E.; Arbuzov, A. B.; Banzarov, V.Sh.; Baratt, A.; Барков, Л.М.; Bogdan, Andrey; Bondar, A.; Bondarev, D.V.; Eidelman, S.; Epifanov, D.; Fedotovich, G. V.; Gabyshev, N.; Gorbachev, D.A.; Grebenuk, A.A.; Grigoriev, D.N.; Hughes, V. W.; Ignatov, F.V.; Казанин, В. Ф.; Khazin, B. I.; Krokovny, P.; Kuraev, É. A.; Kurdadze, L.M.; Kuzmin, A.; Lischenko, Yu.E; Logashenko, I.B.; Lukin, P.; Mikhailov, K.; Miller, J.; Milstein, A. I.; Nikulin, M. A.; Попов, А. С.; Roberts, B. L.; Root, N.; Ryskulov, N.M.; Shatunov, Yu. M.; Shwartz, B.; Sibidanov, A.; Sidorov, V.; Skrinsky, A.N.; Smakhtin, V.; Solodov, E. P.; Stepanov, P.Yu.; Thompson, J.; Zaitsev, A.

doi:10.1016/j.physletb.2003.10.108

Cited by 247 publications

(228 citation statements)

References 16 publications

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“…An intermediate improvement has appeared in the published document [3] and an additional improvement has become available in 2004 [4]. We have concluded that the most recent CMD-2 results imply only a small change in the estimate of the hadronic contribution [5].…”

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confidence: 98%

“…We obtain a value of the hadronic contribution to the running of the QED fine structure constant of [1] to 0.00 347 and the relative uncertainty has decreased from 2.3% to 0.9%. The change of the uncertainty corresponds to the change of precision from the preliminary CMD-2 [2] data to the combination of published CMD-2 [4] and KLOE [6] data. The change of the value and the uncertainty of the hadronic contribution to the running of the QED fine structure constant at m 2 Z is very small.…”

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confidence: 99%

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Low energy hadronic contribution to the QED vacuum polarization

Burkhardt

Pietrzyk

2005

Phys. Rev. D

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Recent improvements in the low energy e e ÿ annihilation data and their influence on the determination of the hadronic contribution to the running of the QED fine structure constant at m Z are discussed. Using CMD-2 and KLOE measurements in the region we obtain 5 had s 0:02 758 0:00 035 at s m 2 Z . DOI: 10.1103/PhysRevD.72.057501 PACS numbers: 13.85.Lg, 13.66.Jn, 12.15.Lk In the year 2001, we published an updated evaluation of the hadronic contribution to the running of the QED fine structure constant [1], based on a dispersion integral using a parametrization of the measured cross section of e e ÿ ! hadrons. We obtained a hadronic contribution of 5 had s 0:02 761 0:00 036 at s m 2 Z . Our parametrization in the c.m. energy region of the , the contribution of the ÿ final state from threshold to 1.8 GeV, was based on a pion form factor parametrization obtained by the CMD-2 Collaboration which used results of their measurements in the c.m. energy region between 0.61 and 0.96 GeV at the VEPP-2M collider [2]. The overall uncertainty of the region integral, including the statistical uncertainty, was 2.3% (that of ÿ ee in [2]) in our analysis.Since then, the CMD-2 Collaboration improved the treatment of radiative corrections twice. An intermediate improvement has appeared in the published document [3] and an additional improvement has become available in 2004 [4]. We have concluded that the most recent CMD-2 results imply only a small change in the estimate of the hadronic contribution [5].Recently, the KLOE Collaboration [6] has measured the cross section of e e ÿ ! ÿ with high statistical accuracy in small energy bins using the ''radiative return'' from the resonance to the in the ÿ mass range between 0.59 and 0.97 GeV.We have been repeatedly asked to update our previous analysis and to comment on and quantify the influence of recent low energy measurements by KLOE and CMD-2 on our results. We find that the actual change turns out to be very small. Thus, we have decided to submit this work as a brief report. To the extent that this report is an update of a previously published article, the choice is not to unnecessarily repeat the discussion for energy regions which did not change.In our 2001 analysis, we used the parametrization of the pion form factor obtained by the CMD-2 Collaboration.The contribution of the new results on 5 had m 2 Z is now obtained by direct integration between measured KLOE and CMD-2 data points separately. For CMD-2 we use the ''bare'' cross section and for KLOE the pion form factor data. These are quantities in which the vacuum polarization corrections have been removed. The small contribution from lower and higher energies, not covered by new data, is evaluated as previously using the CMD-2 parametrization of the pion form factor. We treat the systematic uncertainties as fully correlated between different c.m. energies within the CMD-2 experiment. For the integration of the KLOE data, we constructed a covariance matrix based on the statistical covariance matrix with the addition of fu...

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confidence: 98%

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confidence: 99%

Low energy hadronic contribution to the QED vacuum polarization

Burkhardt

Pietrzyk

2005

Phys. Rev. D

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“…The analysis based on the τ decay data and recent e + e − data from SND collaboration [5] provide the SM results which are in good agreement with the experimental one. The results based on the e + e − data published by the CMD [12] and KLOE [13] data support bigger difference between SM prediction and (g-2) Collaboration result. Theoretically, the τ decay data is found [21] to be more compatible with expectations based on high-scale α s (M Z ) determinations; the electroproduction data (CMD, KLOE), in contrast, requires significantly lower α s (M Z ).…”

Section: Phenomenological Estimates Of the Lo Hadronic Contributions mentioning

confidence: 63%

“…The most recent estimates of the dispersion integral for the 2π-channel in the energy range 0.39 < t π < 0.97 GeV 2 which are based on the e + e − experimental results are following a ππ µ = (378.6 ± 5.0) · 10 −10 CMD2 (2003) [12], a ππ µ = (375.6 ± 5.7) · 10 −10 KLOE (2004) [13], a ππ µ = (385.6 ± 5.2) · 10 −10 SND (2005) [5].…”

Section: Phenomenological Estimates Of the Lo Hadronic Contributions mentioning

confidence: 99%

Hadronic corrections to muon anomalous magnetic moment within the instanton liquid model

Dorokhov

2007

Nuclear Physics A

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The current status of the muon anomalous magnetic moment problem is briefly presented. The corrections to muon anomaly coming from the effects of hadronic vacuum polarization, Z * γγ * effective vertex and light-by-light scattering are estimated within the instanton model of QCD vacuum. The study of anomalous magnetic moments (AMM) of leptons, a = (g S −2)/2, have played an important role in the development of the standard model (SM). At present accuracy the electron AMM due to small electron mass is sensitive only to quantum electrodynamic (QED) contributions. The theoretical error [1] is dominated by the uncertainty in the input value of the QED coupling α ≡ e 2 /(4π). Thus, the electron AMM provides the best observable for determining the fine coupling constant α −1 = 137.035 998 83(51).(Compared to the electron, the muon AMM has a relative sensitivity to heavier mass scales which is typically proportional to (m µ /m e ) 2 . 1 At present level of accuracy, the muon AMM gives an experimental sensitivity to virtual W and Z gauge bosons as well as a potential sensitivity to other, as yet unobserved, particles in the few hundred GeV/c 2 mass range. The muon AMM is known to an unprecedented accuracy of order of 1 ppm. The * Presented at XLV Cracow School of Theoretical Physics, Zakopane, Poland June 3-12, 2005. 1 The τ -lepton AMM due to τ 's highest mass is the best for searching for manifestation of effects beyond SM, however, τ -lepton is short living particle, so it is not easy to make experiment with good enough accuracy.(1)

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“…Alternatively, CVC relates the properties of the π + π − system produced in e + e − → π + π − to those of the π − π 0 system produced in τ − → π − π 0 ν τ decay; thus, using CVC and correcting for isospin-violating effects, τ data have also been used to obtain a more precise prediction for a had,LO µ [2,4]. Recently, data on e + e − → π + π − has become available from the CMD-2, KLOE, and SND experiments [5,6,7,8]. Data on τ decays is available from the ALEPH [9,10], CLEO [11], and OPAL [12] experiments.…”

Section: Introductionmentioning

confidence: 99%

A High Statistics Study of the Decay τ−→π−π0ντ

Fujikawa

2006

Nuclear Physics B - Proceedings Supplements

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We report a measurement of the branching fraction for τ − → π − π 0 ν τ and the invariant mass spectrum of the resulting π − π 0 system using 72.2 fb −1 of data recorded by the Belle detector at the KEKB e + e − collider. The branching fraction obtained is (25.15 ± 0.04 ± 0.31)%, where the first error is statistical and the second is systematic. The unfolded π − π 0 mass spectrum is used to determine resonance parameters for the ρ(770), ρ ′ (1450), and ρ ′′ (1700) mesons. We also use this spectrum to estimate the hadronic contribution to the anomalous magnetic moment of the muon.

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Update: A reanalysis of hadronic cross section measurements at CMD-2

Cited by 247 publications

References 16 publications

Low energy hadronic contribution to the QED vacuum polarization

Low energy hadronic contribution to the QED vacuum polarization

Hadronic corrections to muon anomalous magnetic moment within the instanton liquid model

A High Statistics Study of the Decay τ−→π−π0ντ

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