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arXiv · 1110.2483

Precision NNLO determination of alpha_s(M_Z) using an unbiased global parton set

Richard D. Ball·Valerio Bertone·Luigi Del Debbio·Stefano Forte·Alberto Guffanti·Jose I. Latorre·Simone Lionetti·Juan Rojo·Maria Ubiali
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Abstract

We determine the strong coupling alpha_s at NNLO in perturbative QCD using the global dataset input to the NNPDF2.1 NNLO parton fit: data from neutral and charged current deep-inelastic scattering, Drell-Yan, vector boson production and inclusive jets. We find alpha_s(M_Z)=0.1173+- 0.0007 (stat), where the statistical uncertainty comes from the underlying data and uncertainties due to the analysis procedure are negligible. We show that the distribution of alpha_s values preferred by different experiments in the global fit is statistically consistent, without need for rescaling uncertainties by a "tolerance" factor. We show that if deep-inelastic data only are used, the best-fit value of alpha_s is somewhat lower, but consistent within one sigma with the global determination. We estimate the dominant theoretical uncertainty, from higher orders corrections, to be Delta alpha_s (pert) ~ 0.0009.

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Richard D. Ball, Valerio Bertone, Luigi Del Debbio, Stefano Forte, Alberto Guffanti, Jose I. Latorre, Simone Lionetti, Juan Rojo, Maria Ubiali. 2011-10-11. Precision NNLO determination of alpha_s(M_Z) using an unbiased global parton set. https://doi.org/10.1016/j.physletb.2011.11.053

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