Study of Monte Carlo approach to experimental uncertainty propagation with MSTW 2008 PDFs

Abstract

We investigate the Monte Carlo approach to propagation of experimental uncertainties within the context of the established "MSTW 2008" global analysis of parton distribution functions (PDFs) of the proton at next-to-leading order in the strong coupling. We show that the Monte Carlo approach using replicas of the original data gives PDF uncertainties in good agreement with the usual Hessian approach using the standard Delta(chi^2) = 1 criterion, then we explore potential parameterisation bias by increasing the number of free parameters, concluding that any parameterisation bias is likely to be small, with the exception of the valence-quark distributions at low momentum fractions x. We motivate the need for a larger tolerance, Delta(chi^2) > 1, by making fits to restricted data sets and idealised consistent or inconsistent pseudodata. Instead of using data replicas, we alternatively produce PDF sets randomly distributed according to the covariance matrix of fit parameters including appropriate tolerance values, then we demonstrate a simpler method to produce an arbitrary number of random predictions on-the-fly from the existing eigenvector PDF sets. Finally, as a simple example application, we use Bayesian reweighting to study the effect of recent LHC data on the lepton charge asymmetry from W boson decays.

37 pages, 17 figures. v2: version published in JHEP. Supplementary material at http://mstwpdf.hepforge.org/random/

References in corpus (5)

• Parton distributions for the LHC
• Vector boson production at hadron colliders: a fully exclusive QCD calculation at NNLO
• Determination of the strange quark density of the proton from ATLAS measurements of the W->l nu and Z->ll cross sections
• Inclusive $W$ and $Z$ production in the forward region at $\sqrt{s}=7$ TeV
• Parton Distribution Uncertainties using Smoothness Prior

Cited by in corpus (26)

• LHAPDF6: parton density access in the LHC precision era
• The Path to Proton Structure at One-Percent Accuracy
• The PDF4LHC21 combination of global PDF fits for the LHC Run III
• Snowmass 2021 whitepaper: Proton structure at the precision frontier
• Searches for the $Z\gamma$ decay mode of the Higgs boson and for new high-mass resonances in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for Dark Matter Produced in Association with a Higgs Boson Decaying to $b\bar{b}$ using 36 fb${}^{-1}$ of $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS Detector
• Nuclear Structure Functions at a Future Electron-Ion Collider
• Fiducial Higgs and Drell-Yan distributions at N${}^3$LL${}^{\prime }$+NNLO with RadISH
• Search for dark matter in association with a Higgs boson decaying to $b$-quarks in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
• Search for dark matter in association with an energetic photon in pp collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector
• Updated QCD global analysis of single transverse-spin asymmetries I: Extracting $\tilde{H}$, and the role of the Soffer bound and lattice QCD
• Towards the three-dimensional parton structure of the pion: Integrating transverse momentum data into global QCD analysis
• Parton distributions need representative sampling
• Search for contact interactions using the inclusive jet pT spectrum in pp collisions at sqrt(s) = 7 TeV
• Search for new phenomena in events containing a same-flavour opposite-sign dilepton pair, jets, and large missing transverse momentum in $\sqrt{s}=13$ TeV pp collisions with the ATLAS detector
• NLO electroweak corrections to doubly-polarized $W^{+}{W}^{-}$ production at the LHC
• Artificial neural network modelling of generalised parton distributions
• NNLL soft and Coulomb resummation for squark and gluino production at the LHC
• A Stress Test of Global PDF Fits: Closure Testing the MSHT PDFs and a First Direct Comparison to the Neural Net Approach
• Probing gluon helicity with heavy flavor at the EIC
• Reducing the Top Quark Mass Uncertainty with Jet Grooming
• Combination of aN${}^3$LO PDFs and implications for Higgs production cross-sections at the LHC
• Detecting LHC Neutrinos at Surface Level
• Measurement of exclusive pion pair production in proton-proton collisions at $\sqrt{s}=7$ TeV with the ATLAS detector
• New insights from the flavor dependence of quark transverse momentum distributions in the pion
• Assessing the Impact of Fitting Methodology at aN${}^3$LO with FPPDF: an Open Source Tool for Extracting Parton Distribution Functions in the Hessian Approach