W/Z+Jets Production Cross Section Ratio as a New Physics Search with the ATLAS Detector at CERN.
Author: James D. Pearce
Publisher:
Published: 2013
Total Pages:
ISBN-13: 9780494883419
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Measurement of the Production Cross Section of Jets in Association with a Z Boson in 8 TeV Proton-proton Collisions with the ATLAS Detector
Author: Rodger Mantifel
Publisher:
Published: 2017
Total Pages:
ISBN-13:
DOWNLOAD EBOOK"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." --
A Measurement of the Ratio of the W+1 Jet and Z+1 Jet Cross Sections Using the ATLAS Detector at the LHC.
Author: James Christopher Buchanan
Publisher:
Published: 2012
Total Pages:
ISBN-13:
DOWNLOAD EBOOKThe 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.
A Measurement of the Ratio of the Production Cross Sections for W and Z Bosons in Association with Jets with the ATLAS Detector
Author:
Publisher:
Published: 2014
Total Pages:
ISBN-13:
DOWNLOAD EBOOKIn 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.
Jet Calibration, Cross Section Measurements and New Physics Searches with the ATLAS Experiment Within the Run 2 Data
Author: Robert Hankache
Publisher:
Published: 2019
Total Pages: 0
ISBN-13:
DOWNLOAD EBOOKThe Standard Model is the current theory used to describe the elementary particles and their fundamental interactions (except the gravity). My PhD within the ATLAS experiment put this model under test using objects called jets, to study final state particles that interact through the strong force. First, I contributed to a method of jet calibration aiming at calibrating the energy scale of jets in the forward region of the detector with respect to central region. I improved the calibration by making it faster and more precise. Next, I worked on a search analysis of new physics using events with two jets. The Standard Model predicts a smooth distribution of the invariant mass of di-jets, hence we search for a bump which could come from a new particle. Since no significant bump is found, we put limits on signals as predicted by Beyond Standard Model theories and on model-independent signals. Last, I developed a new physics analysis measuring the leading (highest in transverse momentum) jet differential cross-section as a function of transverse momentum and rapidity. The challenge was to factorize the detector effects (resolution and acceptance) from the observable, which I did using a new unfolding technique. I also worked on the theoretical predictions calculation which was very challenging to perform and needed the implementation of special regularizations. The measurement and the predictions are then compared and tensions are observed due to the difficulties of theoretical predictions calculation.
A Beauty-ful Boson
Author: Giulia Di Gregorio
Publisher: Springer Nature
Published: 2023-01-01
Total Pages: 229
ISBN-13: 3031200136
DOWNLOAD EBOOKThe analysis described in this thesis is the search for the Higgs boson, decaying into bb pair, in the associated production with a vector boson, in the extreme Higgs boson transverse momentum region where the Higgs boson is reconstructed using the large-R jet technique. The use of the large-R jets allows to add a part of the phase space unexplored so far, which is particularly sensitive to possible new physics. The analysed data have been collected at LHC by the ATLAS detector between 2015 and 2018 at a centre-of-mass energy of √s = 13 TeV. The same dataset has been used to perform the differential pp → ZH and pp → WH cross-section measurements used to extract the information on the Higgs couplings and to put limits on Beyond the Standard Model effects. Furthermore the analysis has been re-used to perform a cross-section measurement of the diboson ZZ and WZ processes because the diboson and the Higgs processes have a similar topology. For the first time the ZZ(bb) and WZ(bb) cross-sections are measured at √s = 13 TeV and the observed cross-section measurements are consistent with the Standard Model predictions.
Measurements of the W Production Cross Sections in Association with Jets with the ATLAS Detector
Author:
Publisher:
Published: 2015
Total Pages:
ISBN-13:
DOWNLOAD EBOOKThis study presents cross sections for the production of a W boson in association with jets, measured in proton-proton collisions at √s = 7 TeV with the ATLAS experiment at the large hadron collider. With an integrated luminosity of 4.6fb-1, this data set allows for an exploration of a large kinematic range, including jet production up to a transverse momentum of 1TeV and multiplicities up to seven associated jets. The production cross sections for W bosons are measured in both the electron and muon decay channels. Differential cross sections for many observables are also presented including measurements of the jet observables such as the rapidities and the transverse momenta as well as measurements of event observables such as the scalar sums of the transverse momenta of the jets. As a result, the measurements are compared to numerous QCD predictions including next-to-leading-order perturbative calculations, resummation calculations and Monte Carlo generators.
Particle Physics Reference Library
Author: Christian W. Fabjan
Publisher: Springer Nature
Published: 2020
Total Pages: 1083
ISBN-13: 3030353184
DOWNLOAD EBOOKThis second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access
A Measurement of the Ratio of Production Cross Sections for W+1 Jet to W+0 Jets at [square Root of S]
Author: Tacy Marie Joffe-Minor
Publisher:
Published: 1997
Total Pages:
ISBN-13:
DOWNLOAD EBOOKThe QCD corrections to W production associated with a jet are studied using the ratio of W + 1 Jet to W + 0 Jets cross sections for a jet with a transverse energy of 25 GeV. The measured ratio of $0.096\pm0.005\sp{stat}\pm0.008\sp{syst}$ is significantly higher than the theoretical predictions of Giele et al. of 0.053. This discrepancy is at least partly due to the relatively unconstrained gluon distribution of the proton.
