Measurements of event shapes and azimuthal correlations are presented for events where a Z boson is produced in association with jets in protonaproton collisions. The data collected with the CMS ...detector at the CERN LHC at s = 7 TeV correspond to an integrated luminosity of 5.0 fb - 1 . The analysis provides a test of predictions from perturbative QCD for a process that represents a substantial background to many physics channels. Results are presented as a function of jet multiplicity, for inclusive Z boson production and for Z bosons with transverse momenta greater than 150 GeV, and compared to predictions from Monte Carlo event generators that include leading-order multiparton matrix-element (with up to four hard partons in the final state) and next-to-leading-order simulations of Z + 1-jet events. The experimental results are corrected for detector effects, and can be compared directly with other QCD models.
A measurement is presented of the inelastic protonaproton cross section at a centre-of-mass energy of s = 7 TeV . Using the CMS detector at the LHC, the inelastic cross section is measured through ...two independent methods based on information from (i) forward calorimetry (for pseudorapidity 3 200 MeV / c . The measurements cover a large fraction of the inelastic cross section for particle production over about nine units of pseudorapidity and down to small transverse momenta. The results are compared with those of other experiments, and with models used to describe high-energy hadronic interactions.
Results are reported from a search for the anomalous production of highly boosted Z bosons with large transverse momentum and decaying to mu + mu - . Such Z bosons may be produced in the decays of ...new heavy particles. The search uses pp collision data at s = 7 TeV , corresponding to an integrated luminosity of 5.0 fb - 1 recorded with the CMS detector. The shape of the observed transverse momentum distribution of Z bosons is consistent with standard model expectations. Constraints are obtained on models predicting the production of excited quarks decaying via electroweak processes. Assuming a compositeness scale that is equal to the excited quark mass as well as transition coupling strengths between Z bosons and excited quarks that are equal to standard model couplings to quarks, masses of excited quarks below 1.94 TeV are excluded at the 95% confidence level. For excited quark production via a novel contact interaction, masses below 2.22 TeV are excluded, even if the excited quarks do not couple to gluons.
Fabrication of printed circuit boards (PCBs) in high-radiation areas requires new technologies. The CMS detector in the CERN Large Hadron Collider will have portions in high-radiation environment. ...The preshower detector in front of the endcap electromagnetic calorimeter is such an area. During the past several years, the emphasis has been put on the research and development of individual components of the preshower detector. Several prototypes of PCBs were manufactured on ceramic substrates. The final prototype was a high-quality product with the ceramic board meeting all specifications, including the adherence of metallic pastes, the resistivity of the metallic lines and the precision of the laser cutting. The Yerevan Physics Institute in collaboration with the MARS Factory, Rubin L. Tech. JSC and Yerevan Telecommunication Research Institute made 4.500 units of the ceramics PCBs and are now being incorporated in the preshower detector. This article describes in detail the R&D for the technology of thick film printing on a ceramic substrate with different pastes and the precise cutting of ceramic plates by a laser.
Heavy ion physics programme in CMS Baur, G.; Bedjidian, M.; E.Bonner, B. ...
The European physical journal. C, Particles and fields,
07/2004, Letnik:
32, Številka:
S2
Journal Article
A measurement of the double-differential inclusive dijet production cross section in proton-proton collisions at inline image is presented as a function of the dijet invariant mass and jet rapidity. ...The data correspond to an integrated luminosity of 36 pbsuper-1, recorded with the CMS detector at the LHC. The measurement covers the dijet mass range 0.2 TeV to 3.5 TeV and jet rapidities up to
A search for physics beyond the standard model in events with at least three leptons and any number of jets is presented. The data sample corresponds to 35 pb super(-1 of integrated luminosity in pp ...collisions at inline image collected by the CMS experiment at the LHC. A number of exclusive multileptonic channels are investigated and standard model backgrounds are suppressed by requiring sufficient missing transverse energy, invariant mass inconsistent with that of the Z boson, or high jet activity. Control samples in data are used to ascertain the robustness of background evaluation techniques and to minimise the reliance on simulation. The observations are consistent with background expectations. These results constrain previously unexplored regions of supersymmetric parameter space.)
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