Reevaluation of the Hadronic Contribution to Α(m
نویسنده
چکیده
We reevaluate the hadronic part of the electromagnetic vacuum expectation value using the standard dispersion integral approach that utilizes the hadronic cross section measured in e + e − experiments as input. Previous analyses are based upon point-by-point trapezoidal integration which does not treat experimental errors in an optimal way. We use a technique that weights the experimental inputs by their stated uncertainties, includes correlations, and incorporates some refinements. We find the five-flavor hadronic contribution to the fractional change in the electromagnetic coupling constant at q 2 = M 2 Z , ∆α(M 2 Z), to be 0.02752 ± 0.00046, which leads to a value of the electromagnetic coupling constant, α −1 (M 2 Z) = 128.96±0.06.
منابع مشابه
1 99 7 KEK - TH - 530 hep - ph / 9708227 August 1997 Pseudoscalar pole terms in the hadronic light - by - light scattering contribution to muon g − 2
The pseudoscalar pole contribution is the dominant source of the O(α 3) hadronic light-by-light scattering effect in muon g − 2. We have examined this contribution taking account of the off-shell structure of the pseudoscalar-photon-photon anomaly vertex deduced from available experimental data. Our work leads to an improved estimate, −79.2 (15.4) × 10 −11 , for the total hadronic light-by-ligh...
متن کاملReevaluation of the Hadronic Contribution to c~(Mi)*
We reevaluate the haclronic part of the electromagnetic vacuum expectation value using the standard dispersion integral a,pproacli that utilizes the liaclronic _ cross section measured in e+eexperiments as input. Previous analyses are lmsecl upon point-by-point trapezoidal integration which does not treat experinienta.1 errors in an optimal way. We use a technique that weights the experimental ...
متن کاملMULTIHADRON PRODUCTION FOR e e FOR FROM 50 TO 61 GeV, C. M. ENERGIES AND COMPARISON WITH MULTIHADRON PRODUCTION IN HADRONIC INTERACTIONS
Average values of< 1- T >where T is the thrust are presented for e: e: AMY data and are compared with their values in hadronic interactions. As far as possible, similar analysis techniques have been employed in the two different interactions. Similar variation with E is observed for this average in both data. The values of < PT> and < PL > relative to the thrust axis in e e are simila...
متن کاملA determination of the QED coupling at the Z pole
We critically examine the evaluation of the hadronic contribution to the running of the QED coupling, α, from Q 2 = 0 to Q 2 = M 2 Z. Using data for e + e − → hadrons we find that α(M 2 Z) −1 = 128.99 ± 0.06, as compared to the existing value of 128.87 ± 0.12.
متن کاملar X iv : h ep - p h / 98 12 37 0 v 1 1 5 D ec 1 99 8 1 Evaluation of α ( M 2 Z ) and ( g − 2 ) μ
This talk summarizes the recent developments in the evaluation of the leading order hadronic contributions to the running of the QED fine structure constant α(s), at s = M Z, and to the anomalous magnetic moment of the muon (g−2)μ. The accuracy of the theoretical prediction of these observables is limited by the uncertainties on the hadronic contributions. Significant improvement has been achie...
متن کامل