David d'Enterria, Juan Rojo
The impact of isolated-photon data from proton-(anti)proton collisions at
RHIC, SppbarS, Tevatron and LHC energies, on the parton distribution functions
of the proton is studied using a recently developed Bayesian reweighting
method. The impact on the gluon density of the 35 existing isolated-gamma
measurements is quantified using next-to-leading order (NLO) perturbative QCD
calculations complemented with the NNPDF2.1 parton densities. The NLO
predictions are found to describe well most of the datasets from 200 GeV up to
7 TeV centre-of-mass energies. The isolated-photon spectra recently measured at
the LHC are precise enough to constrain the gluon distribution and lead to a
moderate reduction (up to 20%) of its uncertainties around fractional momenta
x~0.02. As a particular case, we show that the improved gluon density reduces
the PDF uncertainty for the Higgs boson production cross section in the
gluon-fusion channel by more than 20% at the LHC. We conclude that present and
future isolated-photon measurements constitute an interesting addition to
coming global PDF analyses.
View original:
http://arxiv.org/abs/1202.1762
No comments:
Post a Comment