Journal
JOURNAL OF HIGH ENERGY PHYSICS
Volume -, Issue 8, Pages -Publisher
SPRINGER
DOI: 10.1007/JHEP08(2012)052
Keywords
QCD Phenomenology; Deep Inelastic Scattering (Phenomenology)
Categories
Funding
- London Centre for Terauniverse Studies (LCTS)
- European Research Council [267352]
- STFC [ST/J000515/1] Funding Source: UKRI
- Science and Technology Facilities Council [ST/J000515/1] Funding Source: researchfish
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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.
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