2011 QCD and High Energy Interactions - Rencontres de Moriond ...

1 Introduction
Most of the LHC results presented at Moriond QCD 2011 are based on the full data set collected by
the experiments in 2010, their first full year of operation. The useful luminosity (~35 pb -1 ) collected
by ATLAS and CMS in pp collisions at a centre of mass energy of 7 TeV, though much lower than
that analysed at TEVATRON (~6 fb -1 ), already provides a higher sensitivity to the highest energy
phenomena thanks to the higher centre of mass energy. The pp data collected by LHCb also provide
B meson precisions measurements competitive with TEVATRON and B factories. In addition, the
one month dedicated Heavy Ion Pb-Pb run performed at the end of 2010 at a nucleon-nucleon
centre of mass energy of 2.76 TeV allows the LHC experiments to extend the probe of high density
matter in new domains compared to RHIC. The following summarizes the results obtained in each
of these three fields.
2 High Energy Frontier
The centre of mass energy presently available at LHC provides a 3.5 higher resolution than at
TEVATRON for probing the fundamental constituents of matter. It also makes measurements at the
EW scale more sensitive to low-x parton densities, which therefore need to be controlled with a
higher precision. New combined measurements of H1 and ZEUS performed with the full HERA
I+II data sets (figure 1) improve the control of the initial state at LHC not only in the low x domain,
Figure 1:
Combined inclusive Neutral Current cross-section at HERA (left) and associated PDF QCD fits (right)