PDF dependence of Higgs cross sections at the Tevatron and LHC: response to recent criticism

TL;DR

This paper defends the current Higgs exclusion limits at the Tevatron and LHC by analyzing the dependence of Higgs production cross sections on PDFs and alpha_S, emphasizing the importance of jet data and consistent uncertainty treatment.

Contribution

It demonstrates the role of Tevatron jet data in constraining gluon PDFs and clarifies that Higgs cross-section uncertainties are not underestimated, countering recent criticisms.

Findings

Tevatron jet data effectively discriminate between high-x gluon PDFs.

Higgs cross-section uncertainties due to PDFs and alpha_S are adequately estimated.

Consistent treatment of luminosity uncertainties is crucial for accurate limits.

Abstract

We respond to some criticism questioning the validity of the current Standard Model Higgs exclusion limits at the Tevatron, due to the significant dependence of the dominant production cross section from gluon-gluon fusion on the choice of parton distribution functions (PDFs) and the strong coupling (alpha_S). We demonstrate the ability of the Tevatron jet data to discriminate between different high-x gluon distributions, performing a detailed quantitative comparison to show that fits not explicitly including these data fail to give a good description. In this context we emphasise the importance of the consistent treatment of luminosity uncertainties. We comment on the values of alpha_S obtained from fitting deep-inelastic scattering data, particularly the fixed-target NMC data, and we show that jet data are needed for stability. We conclude that the Higgs cross-section uncertainties due to PDFs and alpha_S currently used by the Tevatron and LHC experiments are not significantly underestimated, contrary to some recent claims.