Uncertainty induced by QCD coupling in the CTEQ global analysis of parton distributions
| Autor: | Zhao Li, Jon Pumplin, Pavel Nadolsky, H. L. Lai, Daniel R. Stump, C.-P. Yuan, Joey Huston |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Quantum chromodynamics
Physics Nuclear and High Energy Physics Particle physics Series (mathematics) 010308 nuclear & particles physics High Energy Physics::Phenomenology Tevatron FOS: Physical sciences Parton 01 natural sciences Gluon Quadrature (mathematics) Physics::Fluid Dynamics High Energy Physics - Phenomenology Distribution (mathematics) High Energy Physics - Phenomenology (hep-ph) 0103 physical sciences High Energy Physics::Experiment 010303 astronomy & astrophysics Boson |
| Popis: | We examine the dependence of parton distribution functions (PDFs) on the value of the QCD coupling strength $\alpha_{s}(M_{Z})$. We explain a simple method that is rigorously valid in the quadratic approximation normally applied in PDF fitting, and fully reproduces the correlated dependence of theoretical cross sections on $\alpha_s$ and PDF parameters. This method is based on a statistical relation that allows one to add the uncertainty produced by $\alpha_s$, computed with some special PDF sets, in quadrature with the PDF uncertainty obtained for the fixed $\alpha_s$ value (such as the CTEQ6.6 PDF set). A series of four CTEQ6.6AS PDFs realizing this approach, for $\alpha_s$ values in the interval $0.116 \leq \alpha_{s}(M_{Z}) \leq 0.120$, is presented. Using these PDFs, the combined $\alpha_{s}$ and PDF uncertainty is assessed for theoretical predictions at the Fermilab Tevatron and Large Hadron Collider. Comment: minor changes for publication |
| Databáze: | OpenAIRE |
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