27 research outputs found
Saturation physics at HERA and RHIC: An unified description
One of the frontiers of QCD which are intensely investigated in high energy
experiments is the high energy (small ) regime, where we expect to observe
the non-linear behavior of the theory. In this regime, the growth of the parton
distribution should saturate, forming a Color Glass Condensate (CGC). In fact,
signals of parton saturation have already been observed both in deep
inelastic scattering at HERA and in deuteron-gold collisions at RHIC.
Currently, the description of the experimental data of these experiments is
possible considering different phenomenological saturation models for the two
processes within the CGC formalism. In this letter we analyze the universality
of these dipole cross section parameterizations and verify that they are not
able to describe the HERA and RHIC data simultaneously. We analyze possible
improvements in the parameterizations and propose a new parametrization for the
forward dipole amplitude which allows us to describe quite well the small-
HERA data on structure function as well as the RHIC data on
charged hadron spectra. It is an important signature of the universality of the
saturation physics.Comment: 12 pages, 4 figures. Version to be published in Physics Letters
Measurement of the photon-jet production differential cross section in collisions at \sqrt{s}=1.96~\TeV
We present measurements of the differential cross section dsigma/dpT_gamma
for the inclusive production of a photon in association with a b-quark jet for
photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for
photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is
the photon transverse momentum. The b-quark jets are required to have pT>15 GeV
and rapidity |y_jet| < 1.5. The results are based on data corresponding to an
integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the
Fermilab Tevatron Collider at sqrt(s)=1.96 TeV. The measured cross
sections are compared with next-to-leading order perturbative QCD calculations
using different sets of parton distribution functions as well as to predictions
based on the kT-factorization QCD approach, and those from the Sherpa and
Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.