Proton-proton collisions at √ s = 7 TeV and heavy ion collisions at √ s NN = 2.76 TeV were produced by the LHC and recorded using the ATLAS experiment's trigger system in 2010. The LHC is designed with a maximum bunch crossing rate of 40 MHz and the ATLAS trigger system is designed to record approximately 200 of these per second. The trigger system selects events by rapidly identifying signatures of muon, electron, photon, tau lepton, jet, and B meson candidates, as well as using global event signatures, such as missing transverse energy. An overview of the ATLAS trigger system, the evolution of the system during 2010 and the performance of the trigger system components and selections based on the 2010 collision data are shown. A brief outline of plans for the trigger system in 2011 is presented.

A measurement of inclusive W and Z production cross sections in pp collisions at √ s = 7 TeV is presented. The electron and muon decay channels are analyzed in a data sample collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 36 pb

Spectra of identified charged hadrons are measured in pp collisions at the LHC for √ s = 0.9, 2.76, and 7 TeV. Charged pions, kaons, and protons in the transversemomentum range p T ≈ 0.1-1.7 GeV/c and for rapidities |y| < 1 are identified via their energy loss in the CMS silicon tracker. The average p T increases rapidly with the mass of the hadron and the event charged-particle multiplicity, independently of the center-of-mass energy. The fully corrected p T spectra and integrated yields are compared to various tunes of the PYTHIA 6 and PYTHIA 8 event generators.

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Measurements from the CMS experiment at the LHC of dihadron correlations for charged particles produced in PbPb collisions at a nucleon-nucleon centre-of-mass energy of 2.76 TeV are presented. The results are reported as a function of the particle transverse momenta (p T ) and collision centrality over a broad range in relative pseudorapidity ( η) and the full range of relative azimuthal angle ( φ). The observed two-dimensional correlation structure in η and φ is characterised by a narrow peak at ( η, φ) ≈ (0, 0) from jet-like correlations and a longrange structure that persists up to at least | η| = 4. An enhancement of the magnitude of the short-range jet peak is observed with increasing centrality, especially for particles of p T around 1-2 GeV/c. The long-range azimuthal dihadron correlations are extensively studied using a Fourier decomposition analysis. The extracted Fourier coefficients are found to factorise into a product of single-particle azimuthal anisotropies up to p T ≈ 3-3.5 GeV/c for at least one particle from each pair, except for the second-order harmonics in the most central PbPb events. Various orders of the single-particle azimuthal anisotropy harmonics are extracted for associated particle p