15 research outputs found
Recent Progress in Parton Distributions and Implications for LHC Physics
I outline some of the most recent developments on the global fit to parton
distributions performed by the MRST collaboration.Comment: 6 pages, 7 figures. To appear in proceedings of XIII International
Workshop on Deep Inelastic Scattering, April,27 - May,1, 2005, Madison,
Wisconsin, US
Parton distributions incorporating QED contributions
We perform a global parton analysis of deep inelastic and related hard-scattering data,
including O( QED) corrections to the parton evolution. Although the quality of the fit is
essentially unchanged, there are two important physical consequences. First, the different
DGLAP evolution of u and d type quarks introduces isospin violation, i.e. up 6= dn, which
is found to be unambiguously in the direction to reduce the NuTeV sin2 W anomaly.
A second consequence is the appearance of photon parton distributions
(x,Q2) of the
proton and the neutron. In principle these can be measured at HERA via the deep inelastic
scattering processes eN → e
X; our predictions are in agreement with the present data
Enhanced charm hadroproduction due to nonlinear corrections to the DGLAP equations
We have studied the effects of nonlinear scale evolution of the parton
distribution functions to charm production in collisions at center-of-mass
energies of 5.5, 8.8 and 14 TeV. We find that the differential charm cross
section can be enhanced up to a factor of 4-5 at low . The enhancement is
quite sensitive to the charm quark mass and the renormalization/factorization
scales.Comment: 4 pages, 3 eps-figures. To appear in the proceedings of the
seventeenth international conference on Ultra-Relativistic Nucleus-Nucleus
Collisions (Quark Matter 2004
QCD
We discuss issues of QCD at the LHC including parton distributions, Monte
Carlo event generators, the available next-to-leading order calculations,
resummation, photon production, small x physics, double parton scattering, and
backgrounds to Higgs production.Comment: 115 pages, Latex, 47 figures, to appear in the Report of the ``1999
CERN Workshop on SM Physics (and more) at the LHC'', S. Catani, M. Dittmar,
D. Soper, W.J. Stirling, S. Tapprogge (convenors
Top quark physics in hadron collisions
The top quark is the heaviest elementary particle observed to date. Its large
mass makes the top quark an ideal laboratory to test predictions of
perturbation theory concerning heavy quark production at hadron colliders. The
top quark is also a powerful probe for new phenomena beyond the Standard Model
of particle physics. In addition, the top quark mass is a crucial parameter for
scrutinizing the Standard Model in electroweak precision tests and for
predicting the mass of the yet unobserved Higgs boson. Ten years after the
discovery of the top quark at the Fermilab Tevatron top quark physics has
entered an era where detailed measurements of top quark properties are
undertaken. In this review article an introduction to the phenomenology of top
quark production in hadron collisions is given, the lessons learned in Tevatron
Run I are summarized, and first Run II results are discussed. A brief outlook
to the possibilities of top quark research a the Large Hadron Collider,
currently under construction at CERN, is included.Comment: 84 pages, 32 figures, accepted for publication by Reports on Progress
in Physic
D meson enhancement in pp collisions at the LHC due to nonlinear gluon evolution
When nonlinear effects on the gluon evolution are included with constraints
from HERA, the gluon distribution in the free proton is enhanced at low
momentum fractions, x < 0.01, and low scales, Q^2 < 10 GeV^2, relative to
standard, DGLAP-evolved, gluon distributions. Consequently, such gluon
distributions can enhance charm production in pp collisions at center of mass
energy 14 TeV by up to a factor of five at midrapidity, y \sim 0, and
transverse momentum p_T -> 0 in the most optimistic case. We show that most of
this enhancement survives hadronization into D mesons. Assuming the same
enhancement at leading and next-to-leading order, we show that the D
enhancement may be measured by D^0 reconstruction in the K^-\pi^+ decay channel
with the ALICE detector.Comment: 15 pages, 4 figures, final version accepted by J. Phys.