18,173 research outputs found
Measurements of single top quark production processes with the ATLAS and CMS experiments
No full textThis report contains a brief summary of the latest single top quark production cross-section measurements performed by the ATLAS and CMS
collaborations on pp collisions collected during Run 2 of the LHC. Various results for t−channel, s−channel and W associated single top production
are discussed. Particular attention is given to the main techniques used by the analyses and the main systematic uncertainties limiting these precise measurements
CMS Computing Software and Analysis Challenge 2006
No full textThe CMS (Compact Muon Solenoid) collaboration is making a big effort to test the workflow and the dataflow associated with the data handling model. With this purpose the computing, software and analysis Challenge 2006, namely CSA06, started the 15th of September. It was a 50 million event exercise that included all the steps of the analysis chain, like the prompt reconstruction, the data streaming, calibration and alignment iterative executions, the data distribution to regional sites, up to the end-user analysis. Grid tools provided by the LCG project are also experimented to gain access to the data and the resources by providing a user friendly interface to the physicists submitting the production and the analysis jobs. An overview of the status and results of the CSA06 is presented in this work
A new boson with a mass of 125 GeV observed with the CMS experiment at the Large Hadron Collider
No full textThe Higgs boson was postulated nearly five decades ago within the framework of the standard model of particle physics and has been the subject of numerous searches at accelerators around the world. Its discovery would verify the existence of a complex scalar field thought to give mass to three of the carriers of the electroweak force-the W+, W-, and Z(0) bosons-as well as to the fundamental quarks and leptons. The CMS Collaboration has observed, with a statistical significance of five standard deviations, a new particle produced in proton-proton collisions at the Large Hadron Collider at CERN. The evidence is strongest in the diphoton and four-lepton (electrons and/or muons) final states, which provide the best mass resolution in the CMS detector. The probability of the observed signal being due to a random fluctuation of the background is about 1 in 3 x 10(6). The new particle is a boson with spin not equal to 1 and has a mass of about 1.25 giga-electron volts. Although its measured properties are, within the uncertainties of the present data, consistent with those expected of the Higgs boson, more data are needed to elucidate the precise nature of the new particle
The CMS statistical analysis and combination tool: COMBINE
No full textThis paper describes the Combine software package used for statistical analyses by the CMS Collaboration. The package, originally designed to perform searches for a Higgs boson and the combined analysis of those searches, has evolved to become the statistical analysis tool presently used in the majority of measurements and searches performed by the CMS Collaboration. It is not specific to the CMS experiment, and this paper is intended to serve as a reference for users outside of the CMS Collaboration, providing an outline of the most salient features and capabilities. Readers are provided with the possibility to run Combine and reproduce examples provided in this paper using a publicly available container image. Since the package is constantly evolving to meet the demands of ever-increasing data sets and analysis sophistication, this paper cannot cover all details of Combine. However, the online documentation referenced within this paper provides an up-to-date and complete user
guide
Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery
No full textIn the version of this article initially published, CMS Collaboration author names, affiliations and acknowledgements were omitted and have now been included in the HTML and PDF versions of the article.Publisher versio
A portrait of the Higgs boson by the CMS experiment ten years after the discovery
No full textIn July 2012, the ATLAS and CMS Collaborations at the CERN Large Hadron
Collider announced the observation of a Higgs boson at a mass of around 125
GeV. Ten years later, and with the data corresponding to the production of 30
times larger number of Higgs bosons, we have learnt much more about the
properties of the Higgs boson. The CMS experiment has observed the Higgs boson
in numerous fermionic and bosonic decay channels, established its spin-parity
quantum numbers, determined its mass and measured its production cross sections
in various modes. Here the CMS Collaboration reports the most up-to-date
combination of results on the properties of the Higgs boson, including the most
stringent limit on the cross section for the production of a pair of Higgs
bosons, on the basis of data from proton-proton collisions at a centre-of-mass
energy of 13 TeV. Within the uncertainties, all these observations are
compatible with the predictions of the standard model of elementary particle
physics. Much evidence points to the fact that the standard model is a
low-energy approximation of a more comprehensive theory. Several of the
standard model issues originate in the sector of Higgs boson physics. An order
of magnitude larger number of Higgs bosons, expected to be examined over the
next fifteen years, will help deepen our understanding of this crucial sector.Comment: Replaced with the published version. Added the journal reference and
the DOI. All the figures and tables can be found at
http://cms-results.web.cern.ch/cms-results/public-results/publications/HIG-22-001
(CMS Public Pages). THis version contains the author list and acknowledgment
First results and prospects in B physics at CMS
No full textThe first results in b physics obtained by the CMS collaboration from the data collected in pp collisions at 7 TeV at the LHC. In particular, results are reported on heavy quarkoniun production (J/ψ) and Y), and on inclusive b jet production cross section. Progress on exclusive reconstructions is also mentioned
Performance Study of the CMS Barrel Resistive Plate Chambers with Cosmic Rays
No full textIn October and November 2008, the CMS collaboration conducted a programme of cosmic ray data taking, which has recorded about 270 million events. The Resistive Plate Chamber system, which is part of the CMS muon detection system, was successfully operated in the full barrel. More than 98% of the channels were operational during the exercise with typical detection efficiency of 90%. In this paper, the performance of the detector during these dedicated runs is reported
Luminosity determination using Z boson production at the CMS experiment
No full textData Availability Statement: This manuscript has no associated data or
the data will not be deposited. [Authors’ comment: Release and preser
vation of data used by the CMS Collaboration as the basis for publi
cations is guidedbytheCMSpolicyasstatedinhttps://cms-docdb.cern.
ch/cgibin/PublicDocDB/RetrieveFile?docid=6032&filename=CMSD
ataPolicyV1.2.pdf&version=2. CMS data preservation,re-use and open
access policy.]A preprint version of the article is available at arXiv:2309.01008v2 [hep-ex], https://arxiv.org/abs/2309.01008v2 . Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables can be found at: https://cms-results.web.cern.ch/cms-results/public-results/publications/LUM-21-001 (CMS Public Pages)The measurement of Z boson production is presented as a method to determine the integrated luminosity of CMS data sets. The analysis uses proton–proton collision data, recorded by the CMS experiment at the CERN LHC in 2017 at a center-of-mass energy of 13 TeV . Events with Z bosons decaying into a pair of muons are selected. The total number of Z bosons produced in a fiducial volume is determined, together with the identification efficiencies and correlations from the same data set, in small intervals of 20 pb-1 of integrated luminosity, thus facilitating the efficiency and rate measurement as a function of time and instantaneous luminosity. Using the ratio of the efficiency-corrected numbers of Z bosons, the precisely measured integrated luminosity of one data set is used to determine the luminosity of another. For the first time, a full quantitative uncertainty analysis of the use of Z bosons for the integrated luminosity measurement is performed. The uncertainty in the extrapolation between two data sets, recorded in 2017 at low and high instantaneous luminosity, is less than 0.5%. We show that the Z boson rate measurement constitutes a precise method, complementary to traditional methods, with the potential to improve the measurement of the integrated luminosity.SCOAP
Simplified likelihood for the re-interpretation of public CMS results
No full textIn this note, a procedure for the construction of simplified likelihoods for the re-interpretation of the results of CMS searches for new physics is presented. The procedure relies on the use of a reduced set of information on the background models used in these searches which can readily be provided by the CMS collaboration. A toy example is used to demonstrate the procedure and its accuracy in reproducing the full likelihood for setting limits in models for physics beyond the standard model. Finally, two representative searches from the CMS collaboration are used to demonstrate the validity of the simplified likelihood approach under realistic conditions
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