Heavy-quark vacuum polarization: first two moments of the O(alphas^3 nf^2) contribution

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dc.creatorChetyrkin, K. G.
dc.creatorKuhn, J. H.
dc.creatorMastrolia, P.
dc.creatorSturm, C.
dc.date2004-12-03
dc.date2005-02-03
dc.date.accessioned2026-07-07T11:58:33Z
dc.date.available2026-07-07T11:58:33Z
dc.descriptionThe vacuum polarization due to a virtual heavy quark pair and specifically the coefficients of its Taylor expansion in the external momentum are closely related to moments of the cross section for quark-antiquark pair production in electron-positron annihilation. Relating measurement and theoretically calculated Taylor coefficients, an accurate value for charm- and bottom-quark mass can be derived, once corrections from perturbative QCD are sufficiently well under control. Up to three-loop order these have been evaluated previously. We now present a subset of four-loop contributions to the lowest two moments, namely those from diagrams which involve two internal loops from massive and massless fermions coupled to virtual gluons, hence of order alphas^3 nf^2. The calculation demonstrates the applicability of Laporta's algorithm to four-loop vacuum diagrams with both massive and massless propagators and should be considered a first step towards the full evaluation of the order alphas^3 contribution.
dc.description10 pages, 17 figures; references added for section 1, accepted for publication in Eur. Phys. J. C
dc.identifierhttps://arxiv.org/abs/hep-ph/0412055
dc.identifierhttp://arxiv.org/abs/hep-ph/0412055
dc.identifierEur.Phys.J.C40:361-366,2005
dc.identifierdoi:10.1140/epjc/s2005-02151-y
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/206261
dc.subjectHigh Energy Physics - Phenomenology
dc.titleHeavy-quark vacuum polarization: first two moments of the O(alphas^3 nf^2) contribution
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