6,935 research outputs found
Alignment of the CMS silicon strip tracker during stand-alone commissioning
No full textThis is the Pre-print version of the Article. The official published version of the paper can be accessed from the link below - Copyright @ 2009 IOPThe results of the CMS tracker alignment analysis are presented using the data from cosmic tracks, optical survey information, and the laser alignment system at the Tracker Integration Facility at CERN. During several months of operation in the spring and summer of 2007, about five million cosmic track events were collected with a partially active CMS Tracker. This allowed us to perform first alignment of the active silicon modules with the cosmic tracks using three different statistical approaches; validate the survey and laser alignment system performance; and test the stability of Tracker structures under various stresses and temperatures ranging from +15C to -15C. Comparison with simulation shows that the achieved alignment precision in the barrel part of the tracker leads to residual distributions similar to those obtained with a random misalignment of 50 (80) microns in the outer (inner) part of the barrel.This work has been supported by: the Austrian Federal Ministry of Science and Research; the Belgium Fonds de la Recherche Scientifique and Fonds voor Wetenschappelijk Onderzoek; the Academy of Finland and
Helsinki Institute of Physics; the Institut National de Physique Nucléaire et de Physique des Particules / CNRS, France; the Bundesministerium für Bildung und Forschung, Germany; the Istituto Nazionale di Fisica Nucleare, Italy; the Swiss Funding Agencies; the Science and Technology Facilities Council, UK; the US Department of Energy, and National Science Foundation. Individuals
have received support from the Marie-Curie IEF program (European Union) and the A. P. Sloan Foundation
Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery (Nature, (2022), 607, 7917, (60-68), 10.1038/s41586-022-04892-x)
No full textCorrection to: Nature Published online 4 July 2022 In 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.SCOAP
Combination of inclusive top-quark pair production cross-section measurements using ATLAS and CMS data at = 7 and 8 TeV
No full textA preprint version of this article is available at arXiv:2205.13830v2 [hep-ex], https://arxiv.org/abs/2205.13830 . Submission istory: [v2] Tue, 5 Sep 2023 12:43:58 UTC (484 KB). Comments: 59 pages in total, author lists starting at page 24, 4 figures, 6 tables. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2018-39 and at https://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-18-014/index.html . Report number: CERN-EP-2021-222.A combination of measurements of the inclusive top-quark pair production cross-section performed by ATLAS and CMS in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV at the LHC is presented. The cross-sections are obtained using top-quark pair decays with an opposite-charge electron-muon pair in the final state and with data corresponding to an integrated luminosity of about 5 fb−1 at √s = 7 TeV and about 20 fb−1 at √s = 8 TeV for each experiment. The combined cross-sections are determined to be 178.5±4.7 pb at √s = 7 TeV and 243.3+6.0−5.9 pb at √s = 8 TeV with a correlation of 0.41, using a reference top-quark mass value of 172.5 GeV. The ratio of the combined cross-sections is determined to be R8/7=1.363±0.032. The combined measured cross-sections and their ratio agree well with theory calculations using several parton distribution function (PDF) sets. The values of the top-quark pole mass (with the strong coupling fixed at 0.118) and the strong coupling (with the top-quark pole mass fixed at 172.5 GeV) are extracted from the combined results by fitting a next-to-next-to-leading-order plus next-to-next-to-leading-log QCD prediction to the measurements. Using a version of the NNPDF3.1 PDF set containing no top-quark measurements, the results obtained are mpolet=173.4+1.8−2.0 GeV and αs(mZ)=0.1170+0.0021−0.0018.SCOAP3
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
Measurement of inclusive and differential cross sections for single top quark production in association with a W boson in proton-proton collisions at = 13 TeV
No full textA preprint version of the article is available at arXiv:2208.00924v2 [hep-ex], https://arxiv.org/abs/2208.00924v2 . Comments: Replaced with the published version. Added the journal reference and the DOI. All the figures and tables, including additional supplementary figures, can be found at https://cms-results.web.cern.ch/cms-results/public-results/publications/TOP-21-010 (CMS Public Pages). Report number: CMS-TOP-21-010, CERN-EP-2022-158.Measurements of the inclusive and normalised differential cross sections are presented for the production of single top quarks in association with a W boson in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data used were recorded with the CMS detector at the LHC during 2016-2018, and correspond to an integrated luminosity of 138 fb^{−1}. Events containing one electron and one muon in the final state are analysed. For the inclusive measurement, a multivariate discriminant, exploiting the kinematic properties of the events is used to separate the signal from the dominant tt¯ background. A cross section of 79.2 ± 0.9 (stat) +7.7−8.0 (syst) ± 1.2 (lumi) pb is obtained, consistent with the predictions of the standard model. For the differential measurements, a fiducial region is defined according to the detector acceptance, and the requirement of exactly one jet coming from the fragmentation of a bottom quark. The resulting distributions are unfolded to particle level and agree with the predictions at next-to-leading order in perturbative quantum chromodynamics.SCOAP3
Strategies and performance of the CMS silicon tracker alignment during LHC Run 2
No full textCopyright © 2022 The Author(s). The strategies for and the performance of the CMS silicon tracking system alignment during the 2015–2018 data-taking period of the LHC are described. The alignment procedures during and after data taking are explained. Alignment scenarios are also derived for use in the simulation of the detector response. Systematic effects, related to intrinsic symmetries of the alignment task or to external constraints, are discussed and illustrated for different scenarios
The efficient pricing of CMS and CMS spread derivatives
No full textTwo popular products on the interest rate market are Constant Maturity Swap (CMS) derivatives and CMS spread derivatives. This thesis focusses on the efficient pricing of CMS and CMS spread derivatives, in particular the pricing of CMS and CMS spread options. The notional values for these products are usually quite large, so even small errors when pricing these products can lead to substantial losses. Therefore, the pricing of these products has to be accurate. It is possible to use sophisticated models (e.g. Libor Market Model) to price these products, however the downside is that these models generally have high computational costs; they are not very efficient. To efficiently price CMS options the Terminal Swap Rate (TSR) approach can be used. From this approach TSR models are obtained, we will consider four different TSR models. Two of these TSR models are established in the literature, the other two TSR models are developed in this thesis. The main advantages of a TSR model is that the computational costs are low and that it has good numerical tractability. To price CMS spread options the copula approach is usually used. With the copula approach a pricing formula can be obtained for efficient valuations of CMS spread options. The copula that is considered in this thesis is the Gaussian copula. The TSR models are also a key component in the copula approach, because the marginal distributions are obtained with the help of a TSR model. Furthermore, an alternative approach is considered for the pricing of CMS spread options. The CMS spread options are priced with a relatively simple stochastic volatility model, the displaced diffusion SABR model. The displaced diffusion SABR model is obtained by applying the Markovian projection method to a modification of a two-dimensional version of the well-established SABR model. The calibration of the two-dimensional SABR model is performed with the help of the TSR approach.Applied mathematicsElectrical Engineering, Mathematics and Computer Scienc
Results and prospects with the CMS-TOTEM precision proton spectrometer
No full textWith more than 100 fb−1 recorded during LHC run 2 (2016-2018), the joint CMS-TOTEM Precision Proton Spectrometer (CT-PPS) has started to deliver its first physics results. Located between 200 and 220 m on each side from the CMS detector, it aims at detecting forward scattered protons emerging intact from the interaction, as for instance in central exclusive processes (CEP). In this paper we describe in detail the search for two-photon production of a lepton pair performed with the first 10 fb−1. This result proves the feasibility of operating near-beam detectors at the LHC under standard, high luminosity conditions. In addition, we describe the potential of PPS for future physics studies. © Owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND 4.0).Peer reviewe
Development of the CMS detector for the CERN LHC Run
No full textAbstract: Since the initial data taking of the CERN LHC, the CMS experiment has undergone substantial upgrades and improvements. This paper discusses the CMS detector as it is configured for the third data-taking period of the CERN LHC, Run 3, which started in 2022. The entire silicon pixel tracking detector was replaced. A new powering system for the superconducting solenoid was installed. The electronics of the hadron calorimeter was upgraded. All the muon electronic systems were upgraded, and new muon detector stations were added, including a gas electron multiplier detector. The precision proton spectrometer was upgraded. The dedicated luminosity detectors and the beam loss monitor were refurbished. Substantial improvements to the trigger, data acquisition, software, and computing systems were also implemented, including a new hybrid CPU/GPU farm for the high-level trigger.Abstract: Since the initial data taking of the CERN LHC, the CMS experiment has undergone substantial upgrades and improvements. This paper discusses the CMS detector as it is configured for the third data-taking period of the CERN LHC, Run 3, which started in 2022. The entire silicon pixel tracking detector was replaced. A new powering system for the superconducting solenoid was installed. The electronics of the hadron calorimeter was upgraded. All the muon electronic systems were upgraded, and new muon detector stations were added, including a gas electron multiplier detector. The precision proton spectrometer was upgraded. The dedicated luminosity detectors and the beam loss monitor were refurbished. Substantial improvements to the trigger, data acquisition, software, and computing systems were also implemented, including a new hybrid CPU/GPU farm for the high-level trigger
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