Recent results of the searches for Supersymmetry in final states with one or two leptons at CMS are presented. Many Supersymmetry scenarios, including the Constrained Minimal Supersymmetric extension of the Standard Model (CMSSM), predict a substantial amount of events containing leptons, while the largest fraction of Standard Model background events -which are QCD interactions -gets strongly reduced by requiring isolated leptons. The analyzed data was taken in 2011 and corresponds to an integrated luminosity of approximately L = 1 fb −1 . The center-of-mass energy of the pp collisions was √ s = 7 TeV.
We present the FP420 R&D project, which has been studying
the key aspects of the development and installation of a silicon
tracker and fast-timing detectors in the LHC tunnel at 420 m from
the interaction points of the ATLAS and CMS experiments. These
detectors would measure precisely very forward protons in
conjunction with the corresponding central detectors as a means to
study Standard Model (SM) physics, and to search for and
characterise new physics signals. This report includes a detailed
description of the physics case for the detector and, in particular,
for the measurement of Central Exclusive Production, pp→p+ϕ+p, in which the outgoing protons remain intact and the
central system ϕ may be a single particle such as a SM or MSSM
Higgs boson. Other physics topics discussed are γγ and
γp interactions, and diffractive processes. The report
includes a detailed study of the trigger strategy, acceptance,
reconstruction efficiencies, and expected yields for a particular
pp→pHp measurement with Higgs boson decay in the
bb̄ mode. The document also describes the detector
acceptance as given by the LHC beam optics between the interaction
points and the FP420 location, the machine backgrounds, the new
proposed connection cryostat and the moving (``Hamburg'') beam-pipe
at 420 m, and the radio-frequency impact of the design on the
LHC. The last part of the document is devoted to a description of
the 3D silicon sensors and associated tracking performances, the
design of two fast-timing detectors capable of accurate vertex
reconstruction for background rejection at high-luminosities, and
the detector alignment and calibration strategy.
Commissioning studies of the CMS hadron calorimeter have identified sporadic uncharacteristic noise and a small number of malfunctioning calorimeter channels. Algorithms have been developed to identify and address these problems in the data. The methods have been tested on cosmic ray muon data, calorimeter noise data, and single beam data collected with CMS in 2008. The noise rejection algorithms can be applied to LHC collision data at the trigger level or in the offline analysis. The application of the algorithms at the trigger level is shown to remove 90% of noise events with fake missing transverse energy above 100 GeV, which is sufficient for the CMS physics trigger operation.
The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75 848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented.
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