Lars Sonnenschein

The CMS experiment is a multi-purpose detector successfully operated at the LHC where predominantly pp collisions take place at various centre-of-mass energies up to sqrt(s)=8 TeV so far. Several weeks per year also heavy-ion collisions take place leading to interesting studies in Pb-Pb and p-Pb collisions at sqrt(s_(NN))=2.76 TeV and sqrt(s_(NN))=5.02 TeV centre-of-mass energies per nucleon, respectively. The excellent performance of the accelerator and the experiment allows for dedicated physics measurements over a wide range of subjects, starting from particle identification, encompassing forward physics, Standard Model measurements in multijet, boson, heavy flavour and top quark physics, building the basis for new physics searches interpreted within the framework of various models and theories. These pursued pp physics subjects are complemented by a rich heavy ion physics programme.

The CMS experiment is a multi-purpose detector successfully operated at the LHC where predominantly pp collisions take place at various centre of mass energies up to sqrt(s)=8 TeV at present. Discussed are pp collision results until end of 2011, corresponding to centre of mass energies of up to sqrt(s)=7 TeV. The excellent performance of the accelerator and the experiment allows for dedicated physics measurements over a wide range of subjects, starting from particle identification, encompassing Standard Model measurements in multijet, boson, heavy flavour and top quark physics, building the basis for new physics searches interpreted within the framework of various models and theories.

D0 provides a wealth of measurements conceived for probing perturbative and non-perturbative aspects of QCD, giving an accurate experimental account for Standard Model production processes including jets, leptons and photons and improving the sensitivity and the understanding in searches for new physics. Among the most important subjects are inclusive jet production, vector boson plus jet production, direct photon production and measurements in Minimum Bias events and Double Parton Scattering which are discussed here and compared to theory predictions.

A dedicated cosmic muon Monte-Carlo event generator CMSCGEN has been developed for the CMS experiment. The simulation relies on parameterisations of the muon energy and the incidence angle, based on measured and simulated data of the cosmic muon flux. The geometry and material density of the CMS infrastructure underground and surrounding geological layers are also taken into account. The event generator is integrated into the CMS detector simulation chain of the existing software framework. Cosmic muons can be generated on earth's surface as well as for the detector located 90 m underground. Many million cosmic muon events have been generated and compared to measured data, taken with the CMS detector at its nominal magnetic field of 3.8 T.

A measurement is presented of the flux ratio of positive and negative muons from cosmic ray interactions in the atmosphere, using data collected by the CMS detector at ground level and in the underground experimental cavern. The excellent performance of the CMS detector allowed detection of muons in the momentum range from 5GeV/c to 1TeV/c. For muon momenta below 100GeV/c the flux ratio is measured to be a constant 1.2766 +/-0.0032(stat.) +/-0.0032(syst.), the most precise measurement to date. At higher momenta an increase in the charge ratio is observed, in agreement with models of muon production in cosmic ray showers and compatible with previous measurements by deep underground experiments.

The drift velocity in drift tubes of the CMS muon chambers is a key parameter for the muon track reconstruction and trigger. It needs to be monitored precisely in order to detect any deviation from its nominal value. A change in absolute pressure, a variation of the gas admixture or a contamination of the chamber gas by air affect the drift velocity. Furthermore, the temperature and magnetic field influence its value. First data, taken with a dedicated Velocity Drift Chamber (VDC) built by RWTH Aachen IIIA are presented.

A dedicated cosmic muon Monte-Carlo event generator CMSCGEN has been developed for the CMS experiment. The simulation relies on parameterisations of the muon energy and the incidence angle, based on measured and simulated data of the cosmic muon flux. The geometry and material density of the CMS infrastructure underground and surrounding geological layers are also taken into account. The event generator is integrated into the CMS detector simulation chain of the existing software framework. Cosmic muons can be generated on earth's surface as well as for the detector located 90 m underground. Many million cosmic muon events have been generated and compared to measured data, taken with the CMS detector at its nominal magnetic field of 3.8 T.

The strong coupling constant alpha_s and its dependence on the momentum scale is determined from the p_T dependence of the inclusive jet cross section in ppbar collisions at sqrt(s)=1.96 TeV measured with the D0 experiment. The jet transverse momentum range of 50 < p_T < 145 GeV contributes to the determination. Using perturbative QCD caclulations to order O(alpha_s^3) combined with resummed threshold corrections to order O(alpha_s^4) an alpha_s(M_Z)=0.1161^{+0.0041}_{-0.0048} is obtained. This is the most precise result from a hadron-hadron collider.