Uncertainty induced by QCD coupling in the CTEQ global analysis of parton distributions

By Hung-Liang Lai, J. Huston, Zhao Li, Pavel M. Nadolsky, J. Pumplin, D. Stump, C. Yuan. 2010

202 citations recorded by the source corpus.

We examine the dependence of parton distribution functions (PDFs) on the value of the QCD coupling strengths(MZ). 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 ons and PDF parameters. This method is based on a statistical relation that allows one to add the uncertainty produced bys, computed with some special PDF sets, in quadrature with the PDF uncertainty obtained for the fixeds value (such as the CTEQ6.6 PDF set). A series of four CTEQ6.6AS PDFs realizing this approach, fors values in the interval 0.116 � �s(MZ) � 0.120, is presented. Using these PDFs, the combineds and PDF uncertainty is assessed for theoretical predictions at the Fermilab Tevatron and Large Hadron Collider.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f3476f3c8917fc681962a67234815df68220f167

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Citations in the corpus

Parton distribution benchmarking with LHC data (2012, methodology): “120 for MSTW), and also because αs and PDF uncertainties are added in quadrature instead of being determined exactly in the Hessian or Monte Carlo method (though in the Hessian method the two procedures are equivalent [84]).”
Measurement of Higgs boson production and properties in the WW decay channel with leptonic final states (2013, methodology): “The set of parton distribution functions (PDF) used is CTEQ6L [66] for LO generators, while CT10 [67] is used for next-to-leading-order (NLO) generators.”
Parton distributions for the LHC run II (2014, background): “Clearly, our predictions are not meant to be realistic, however, the effects which we do not include (such as for instance electroweak corrections, or finite top, bottom and charm mass contributions) have a negligible PDF dependence, while αs uncertainties are completely independent of the PDF uncer”
Search for a Higgs boson in the mass range from 145 to 1000 GeV decaying to a pair of W or Z bosons (2015, methodology): “The first level of the CMS trigger system, composed of custom hardware processors, uses information from the calorimeters and the muon detectors to select the most”
The Structure of the Proton in the LHC Precision Era (2017, methodology): “Figure 34: Comparison of the combined PDF+αs uncertainties for the gluon and charm quark PDFs using the full eigenvectors including αs(mZ) in the Hessian matrix (filled error band with dotted borders) and with the separate PDF and αs uncertainties added in quadrature (hatched band with solid borders”
PDF4LHC recommendations for LHC Run II (2015, background): “Indeed, it can be shown [27] that addition of PDF and αs uncertainties in quadrature automatically accounts for the correlation between αs and PDF uncertainties, assuming gaussianity and linear error propagation.”
Constraints on the gluon PDF from top quark pair production at hadron colliders (2013, unknown): “For Hessian PDF sets the addition in quadrature of PDF and αs uncertainties is known to be exact [46], while for Monte Carlo sets it is a good approximation [47].”
Identification of b-quark jets with the CMS experiment (2012, methodology): “The uncertainties related to the parton distribution function (PDF) used to model the hard scattering of the proton-proton collisions are estimated by varying the parameters of the PDF by±1σ with respect to their nominal values and using the PDF4LHC prescription [13, 15].”