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Remarks on the dispersion relations used to calculate Δρ
Phys. Rev. D 51, 6457 – Published 1 June, 1995
DOI: https://doi.org/10.1103/PhysRevD.51.6457
Abstract
We use the operator product expansion to show that nonperturbative QCD corrections to Δρ can be calculated using unsubtracted dispersion relations for either the transverse or the longitudinal vacuum polarization functions. Recent calculations of the nonperturbative contribution to Δρ based on a nonrelativistic calculation of corrections to the tt¯ threshold are inconsistent with this result.
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