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Book A Measurement of W jets Z jets with the ATLAS Detector

Download or read book A Measurement of W jets Z jets with the ATLAS Detector written by Gregory Fletcher and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book A Measurement of the Ratio of the Production Cross Sections for W and Z Bosons in Association with Jets with the ATLAS Detector

Download or read book A Measurement of the Ratio of the Production Cross Sections for W and Z Bosons in Association with Jets with the ATLAS Detector written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the ratio of the production cross sections for W and Z bosons in association with jets has been measured in proton-proton collisions at √s = 7 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is based on the entire 2011 dataset, corresponding to an integrated luminosity of 4.6 fb-1. Inclusive and differential cross-section ratios for massive vector bosons decaying to electrons and muons are measured in association with jets with transverse momentum pT > 30 GeV and jet rapidity.

Book A Measurement of the Ratio of the W 1 Jet and Z 1 Jet Cross Sections Using the ATLAS Detector at the LHC

Download or read book A Measurement of the Ratio of the W 1 Jet and Z 1 Jet Cross Sections Using the ATLAS Detector at the LHC written by James Christopher Buchanan and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The first measurement of the ratio of the W and Z cross sections in association with a single jet, known as the R Jets measurement, is presented. The measurement was performed using 33pb-1 of integrated luminosity, recorded during the year 2010 by the ATLAS detector at the LHC. At this time the LHC was operating at a center-of-mass energy of /s = 7 TeV. The measurement is made as a function of the threshold on the jet transverse momentum, from 30 GeV up to a value of 200 GeV. The motivation for this measurement is outlined in terms of providing a stringent test of the Standard Model of particle physics, as well as a model independent tool for searching for new physics. Data driven tools are developed to perform the measurement and their performance is discussed. The result of the measurement is compared with the predictions of Next-to-Leading order perturbative QCD and found to be in good agreement over the entire range of transverse momenta considered.

Book Measurement of the Production Cross Section of Jets in Association with a Z Boson in 8 TeV Proton proton Collisions with the ATLAS Detector

Download or read book Measurement of the Production Cross Section of Jets in Association with a Z Boson in 8 TeV Proton proton Collisions with the ATLAS Detector written by Rodger Mantifel and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis presents the measurement of the production cross sections of jets in association with a Z boson in proton-proton collisions at √s = 8 TeV with an integrated luminosity of 20.3 fb−1 recorded by the ATLAS experiment at the Large Hadron Collider at CERN. Inclusive and differential Z/[gamma]∗(→ e+e−)+jets cross sections are measured for jets with a transversemomentum pT(jet) > 30 GeV and rapidity |y(jet)| 4.4. Z boson candidates are identified by their decay into electron pairs. In order to stringently probe the modelling of Z/[gamma]∗+jets production by Monte Carlo generators in regions of high-pT phase space typical for Higgs boson decay and searches for new physics, events with high-pT final states are investigated. High-pT final states are defined as events with either pT(Z) 300 GeV or pT(leading jet) > 300 GeV. A set of four observables, sensitive to the topology of the event, are measured for the standard event selection as well as in the regions of high-pT phase space. The results from data are unfolded to particle level and compared to calculations of the matrix element from Monte Carlo generators Alpgen+Pythia and Sherpa interfaced to a parton shower. The results show that Sherpa tends to model Z/[gamma]∗+jets production in high-pT regions of phase space much better than Alpgen+Pythia." --

Book Physics with Jets in Association with a Z Boson in Pp collisions with the ATLAS Detector at the Large Hadron Collider

Download or read book Physics with Jets in Association with a Z Boson in Pp collisions with the ATLAS Detector at the Large Hadron Collider written by and published by . This book was released on 2013 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the measurements of the production cross section of jets in association with a Z boson in pp-collisions at √s = 7 TeV with an integrated luminosity of ∫Ldt = 36-1 and ∫Ldt = 4.6 fb-1 recorded by the ATLAS experiment at the Large Hadron Collider in Geneva. Inclusive and differential Z(→e+e-) + jets cross sections are measured for jets with a transverse momentum pT(jet) > 30 GeV and rapidity |y(jet)|

Book Standard Model Measurements with the ATLAS Detector

Download or read book Standard Model Measurements with the ATLAS Detector written by Jana Nováková and published by Springer Science & Business Media. This book was released on 2013-08-30 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with two main procedures performed with the ATLAS detector at the Large Hadron Collider (LHC). The noise description in the hadronic calorimeter TileCal represents a very valuable technical job. The second part presents a fruitful physics analysis - the cross section measurement of the process p+p → Z0 → τ + τ. The Monte Carlo simulations of the TileCal are described in the first part of the thesis, including a detailed treatment of the electronic noise and multiple interactions (so-called pile-up). An accurate description of both is crucial for the reconstruction of e.g. jets or hadronic tau-jets. The second part reports a Standard Model measurement of the Z0 → τ + τ process with the emphasis on the final state with an electron and a hadronically decaying tau-lepton. The Z0 → τ + τ channel forms the dominant background in the search for Higgs bosons decaying into tau lepton pairs, and thus the good understanding achieved here can facilitate more sensitive Higgs detection.

Book Search for New Phenomena Using W Z b Jets Measurements Performed with the ATLAS Detector

Download or read book Search for New Phenomena Using W Z b Jets Measurements Performed with the ATLAS Detector written by and published by . This book was released on 2015 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Project proposed to use data of the ATLAS experiment, obtained during the 2011 and 2012 data-taking campaigns, to pursue studies of the strong interaction (QCD) and to examine promising signatures for new physics. The Project also contains a service component dedicated to a detector development initiative. The objective of the strong interaction studies is to determine how various predictions from the main theory (QCD) compare to the data. Results of a set of measurements developed by the Tufts team indicate that the dominant factor of discrepancy between data and QCD predictions come from the mis-modeling of the low energy gluon radiation as described by algorithms called parton showers. The discrepancies introduced by parton showers on LHC predictions could even be larger than the effect due to completely new phenomena (dark matter, supersymmetry, etc.) and could thus block further discoveries at the LHC. Some of the results obtained in the course of this Project also specify how QCD predictions must be improved in order to open the possibility for the discovery of something completely new at the LHC during Run-II. This has been integrated in the Run-II ATLAS physics program. Another objective of Tufts studies of the strong interaction was to determine how the hypothesis about an intrinsic heavy-quark component of the proton (strange, charm or bottom quarks) could be tested at the LHC. This hypothesis has been proposed by theorists 30 years ago and is still controversial. The Tufts team demonstrated that intrinsic charms can be observed, or severely constrained, at the LHC, and determine how the measurement should be performed in order to maximize its sensitivity to such an intrinsic heavy-quark component of the proton. Tufts also embarked on performing the measurement that is in progress, but final results are not yet available. They should shade a light of understanding on the fundamental structure of the proton. Determining the nature of dark matter particles, composing about 25% of all the matter in the universe, is one of the most exciting research goals at the LHC. Within this Project, the Tufts team proposed a way to improve over the standard approach used to look for dark matter at the LHC in events involving jets and a large amount of unbalanced energy in the detector (jets+ETmiss). The Tufts team has developed a measurement to test these improvements on data available (ATLAS 2012 dataset), in order to be ready to apply them on the new Run-II data that will be available at the end of 2015. Preliminary results on the proposed measurement indicate that a very high precision can be obtained on results free of detector effects. That will allow for better constrains of dark matter theories and will spare the needs for huge computing resources in order to compare dark matter theories to data. Finally, the Tufts team played a leading role in the development and the organization of the 6Et trigger, the detector component needed to collect the data used in dark matter searches and in many other analyses. The team compared the performance of the various algorithms capable of reconstructing the value of the ETmiss on each LHC collision event, and developed a strategy to commission these algorithms online. Tufts also contributed in the development of the ETmiss trigger monitoring software. Finally, the PI of this Project acted as the co-coordinator of the group of researchers at CERN taking care of the development and the operation of this detector component. The ETmiss trigger is now taking data, opening the possibility for the discovery of otherwise undetectable particles at the LHC.

Book Determining the Jet Energy Scale for ATLAS in the Z Jet Channel

Download or read book Determining the Jet Energy Scale for ATLAS in the Z Jet Channel written by Sundeep Singh and published by . This book was released on 2020 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a determination of the jet energy scale for the ATLAS detector using in-situ measurements. This calibration is critical, as jets are found in many analyses, and the energy measurement of jets contributes significantly to the uncertainty in numerous ATLAS results. The energy of the jet is initially taken to be the detector measurement, but this is lower than the true energy because the detector is calibrated for electromagnetic particles, not jets. One can find a correction to this energy by balancing the jet's transverse momentum against a well-measured reference object. Directly calibrating the calorimeter-level jet to the particle-level is called Direct Balance; here, a different method called the Missing ET Projection Fraction (MPF) method is used instead, which balances the pt of the recoiling system against the reference object. The MPF's pile-up resistant nature makes it more suitable to use in the ATLAS environment. Results for the MPF method in the Z+Jet channel are presented. A relative calibration of data to Monte Carlo simulation is provided, including a complete systematic uncertainty analysis. The uncertainty on the in-situ calibration is reduced to around 1% for most transverse momenta.

Book Measurement of Jets Produced in Top Quark Events Using the Emu Final State with 2 B tagged Jets in Pp Collisions at 8 TeV with the ATLAS Detector

Download or read book Measurement of Jets Produced in Top Quark Events Using the Emu Final State with 2 B tagged Jets in Pp Collisions at 8 TeV with the ATLAS Detector written by Jacquelyn Kay Brosamer and published by . This book was released on 2016 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: The transverse momentum and multiplicity of jets produced in top quark events are measured using 20.3 inverse fb of pp collision data at a center-of-mass energy of 8 tev. Jets are selected from top events requiring an opposite-charge $e\mu$ pair and two b-tagged jets in the final state. The data are corrected to obtain the particle-level fiducial cross section for additional jets with rank 1-4, where rank=1 is the leading additional jet. These distributions are used to obtain the extra jet multiplicity as a function of minimum jet pt threshold. The results are compared with several next to leading order Monte Carlo generators. The resulting measurements can be used to tune Monte Carlo QCD modelling and may also reduce associated modelling uncertainties for LHC top quark physics measurements.

Book Properties of Jets Measured with Charged Particles with the ATLAS Detector at the Large Hadron Collider

Download or read book Properties of Jets Measured with Charged Particles with the ATLAS Detector at the Large Hadron Collider written by Seth Conrad Zenz and published by . This book was released on 2011 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jets are identified and their properties studied, in proton-proton collisions at the Large Hadron Collider at center-of-mass energy √s = 7 TeV, using charged particles measured by the ATLAS Inner Detector. Events are selected using a minimum bias trigger, allowing jets at very low transverse momentum to be observed and the tran- sition to high-momentum fully perturbative jets to be studied. Jets are reconstructed using the anti-kt algorithm applied to charged particles with two radius parameter choices, 0.4 and 0.6. An inclusive charged jet transverse momentum cross section measurement from 4 GeV to 100 GeV is shown, for four ranges in rapidity extending to 1.9, and corrected to charged particle-level truth jets. The transverse momenta and longitudinal momentum fractions of charged particles within jets are measured, along with the charged particle multiplicity and the particle density as a function of radial distance from the jet axis. Comparison of the data with the theoretical models implemented in existing tunings of Monte Carlo event generators indicates reasonable overall agreement between data and Monte Carlo. These comparisons are sensitive to Monte Carlo parton showering, hadronization, and soft physics models.

Book Precision Measurement of Jets at the ATLAS Experiment

Download or read book Precision Measurement of Jets at the ATLAS Experiment written by Gareth John Ashley Brown and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the measurements of jet activity in the rapidity region between a dijet system formed in proton-proton collisions at a centre-of-mass energy of 7 TeV. The data used were collected by the ATLAS detector during 2010 at the Large Hadron Collider at CERN. A number of observables that probe additional quark and gluon radiation in the dijet topology are studied. The development and performance of the monitoring system for the ATLAS calorimeter high level trigger is described. The performance of the jet calibration and a study of the properties of jets in the forward calorimeter is also given. The fraction of events that survive a veto on jets with transverse momentum above a jet veto scale, Q0, in the rapidity region between the dijet system is measured for dijets with mean transverse momentum 50

Book Physics with Electrons in the ATLAS Detector

Download or read book Physics with Electrons in the ATLAS Detector written by Kurt Brendlinger and published by Springer. This book was released on 2018-01-30 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents two production cross-section measurements of pairs of massive bosons using final states with leptons, made with the ATLAS detector at the Large Hadron Collider. The first measurement, performed using data collected in 2012 at center-of-mass energy √ s = 8 TeV, is the first fiducial and differential cross-section measurement of the production of the Higgs Boson when it decays to four charged leptons (electrons or muons). The second measurement is the first fiducial and inclusive production cross-section measurement of WZ pairs at center-of-mass energy √ s = 13 TeV using final states with three charged leptons. A significant portion of the thesis focuses on the methods used to identify electrons from massive boson decay—important for many flagship measurements—and on assessing the efficiency of these particle identification techniques. The chapter discussing the WZ pair cross-section measurement provides a detailed example of an estimate of lepton background in the context of an analysis with three leptons in the final state.