Structure functions

The ambiguous choice of structure functions used for the simulation introduces an uncertainty in the production cross section. The production of heavy objects requires the x values of the incoming partons to be large. The structure functions are best measured at large x thus making the extrapolation to the LHC energy relatively certain.

In [79] the cross section for a 1 TeV Higgs and the major backgrounds were evaluated using PYTHIA with several different structure functions. For the signal the variation was less than 5% and for the backgrounds less than 10%, making the uncertainty from structure functions small compared to other uncertainties.