QCD Radiation in Top-Antitop and Z+Jets Final States PDF Download
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Author: Kiran Joshi
Publisher:
ISBN: 9783319196541
Category :
Languages : en
Pages :
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Book Description
This thesis contains new research in both experimental and theoretical particle physics, making important contributions in each. Two analyses of collision data from the ATLAS experiment at the LHC are presented, as well as two phenomenological studies of heavy coloured resonances that could be produced at the LHC. The first data analysis was the measurement of top quark-antiquark production with a veto on additional jet activity. As the first detector-corrected measurement of jet activity in top-antitop events it played an important role in constraining the theoretical modelling, and ultimately reduced these uncertainties for ATLAS's other top-quark measurements by a factor of two. The second data analysis was the measurement of Z+2jet production and the observation of the electroweak vector boson fusion (VBF) component. As the first observation of VBF at a hadron collider, this measurement demonstrated new techniques to reliably extract VBF processes and paved the way for future VBF Higgs measurements. The first phenomenological study developed a new technique for identifying the colour of heavy resonances produced in proton-proton collisions. As a by-product of this study an unexpected and previously unnoticed correlation was discovered between the probability of correctly identifying a high-energy top and the colour structure of the event it was produced in. The second phenomenological study explored this relationship in more detail, and could have important consequences for the identification of new particles that decay to top quarks.
Author: Kiran Joshi
Publisher:
ISBN: 9783319196541
Category :
Languages : en
Pages :
Get Book Here
Book Description
This thesis contains new research in both experimental and theoretical particle physics, making important contributions in each. Two analyses of collision data from the ATLAS experiment at the LHC are presented, as well as two phenomenological studies of heavy coloured resonances that could be produced at the LHC. The first data analysis was the measurement of top quark-antiquark production with a veto on additional jet activity. As the first detector-corrected measurement of jet activity in top-antitop events it played an important role in constraining the theoretical modelling, and ultimately reduced these uncertainties for ATLAS's other top-quark measurements by a factor of two. The second data analysis was the measurement of Z+2jet production and the observation of the electroweak vector boson fusion (VBF) component. As the first observation of VBF at a hadron collider, this measurement demonstrated new techniques to reliably extract VBF processes and paved the way for future VBF Higgs measurements. The first phenomenological study developed a new technique for identifying the colour of heavy resonances produced in proton-proton collisions. As a by-product of this study an unexpected and previously unnoticed correlation was discovered between the probability of correctly identifying a high-energy top and the colour structure of the event it was produced in. The second phenomenological study explored this relationship in more detail, and could have important consequences for the identification of new particles that decay to top quarks.
Author: Kiran Joshi
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Kiran Joshi
Publisher: Springer
ISBN: 3319196537
Category : Science
Languages : en
Pages : 188
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Book Description
This thesis contains new research in both experimental and theoretical particle physics, making important contributions in each. Two analyses of collision data from the ATLAS experiment at the LHC are presented, as well as two phenomenological studies of heavy coloured resonances that could be produced at the LHC. The first data analysis was the measurement of top quark-antiquark production with a veto on additional jet activity. As the first detector-corrected measurement of jet activity in top-antitop events it played an important role in constraining the theoretical modelling, and ultimately reduced these uncertainties for ATLAS's other top-quark measurements by a factor of two. The second data analysis was the measurement of Z+2jet production and the observation of the electroweak vector boson fusion (VBF) component. As the first observation of VBF at a hadron collider, this measurement demonstrated new techniques to reliably extract VBF processes and paved the way for future VBF Higgs measurements. The first phenomenological study developed a new technique for identifying the colour of heavy resonances produced in proton-proton collisions. As a by-product of this study an unexpected and previously unnoticed correlation was discovered between the probability of correctly identifying a high-energy top and the colour structure of the event it was produced in. The second phenomenological study explored this relationship in more detail, and could have important consequences for the identification of new particles that decay to top quarks.
Author: Jacquelyn Kay Brosamer
Publisher:
ISBN:
Category :
Languages : en
Pages : 198
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Book Description
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.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 5
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Book Description
In this contribution, some of the recent QCD results on jet production from the CDF and D0 experiments in Run II of the Tevatron are discussed. In particular, results include cross section measurements for dijet and trijet production, study of jet substructure and measurements of W/Z+jets cross sections. The measurements are compared with the theoretical predictions. The QCD program at the Tevatron proton-antiproton collider revolves around the jet physics. Jets are collimated sprays of hadrons generated by the fragmentation of partons originating from the hard scattering. The measurements of jets production cross section at the Tevatron provide stringent test of perturbative QCD predictions, information on the strong coupling constant, [alpha]s, and constraints on proton parton distribution functions, PDFs. The deviations from the pQCD predictions could translate into a hint of new physics. In addition, these processes form sizable backgrounds to both, the Standard Model (SM) and beyond SM physics processes. Therefore, good understanding of jets production is essential to perform precise physics measurements or searches for new physics phenomena. In this contribution, a review of some recent QCD results from the CDF [1] and D0 [2] experiments is presented. Various analyses use proton-antiproton collision data from the Fermilab Tevatron at the center of mass energy √s = 1.96 TeV corresponding to integrated luminosities of 0.7 fb−1 to 8 fb−1. The results are corrected for the experimental effects and presented at the 'particle level'. The theory predictions are corrected for the hadronization and underlying effects which are obtained from the parton shower Monte Carlo (MC) simulations.
Author: Douglas William Schouten
Publisher:
ISBN:
Category : Jets (Nuclear physics)
Languages : en
Pages : 0
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Book Description
This thesis presents results for the determination of the QCD jet energy scale and the single top quark cross-section. Hadron jets are the most commonly observed objects in p-p collisions at the Large Hadron Collider at CERN. Because of this, they are part of the final state of almost any process, and are an important part of all searches for extensions of the Standard Model. This thesis presents an in situ determination of the jet energy scale with a systematic uncertainty of less than 3%. Single top quark production at the LHC is a sensitive probe of physics beyond the standard model, and is itself an important background for Higgs searches. In this thesis, data-driven models for important backgrounds to single top quark events are developed, and are used to measure the t-channel single top quark production rate in 35 / picobarns of integrated luminosity.
Author: Thomas Schörner-Sadenius
Publisher: Springer
ISBN: 3319150014
Category : Science
Languages : en
Pages : 554
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Book Description
This comprehensive volume summarizes and structures the multitude of results obtained at the LHC in its first running period and draws the grand picture of today’s physics at a hadron collider. Topics covered are Standard Model measurements, Higgs and top-quark physics, flavour physics, heavy-ion physics, and searches for supersymmetry and other extensions of the Standard Model. Emphasis is placed on overview and presentation of the lessons learned. Chapters on detectors and the LHC machine and a thorough outlook into the future complement the book. The individual chapters are written by teams of expert authors working at the forefront of LHC research.
Author: Caroline Maria Bertsche
Publisher:
ISBN:
Category : Collisions (Nuclear physics)
Languages : en
Pages : 542
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Book Description
Author: John Campbell
Publisher: Oxford University Press
ISBN: 0199652740
Category : Science
Languages : en
Pages : 760
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Book Description
This title provides an in-depth introduction to the particle physics of current and future experiments at particle accelerators. The text provides the reader with an overview of practically all aspects of the strong interaction necessary to understand and appreciate modern particle phenomenology at the energy frontier.
Author: Robert Hankache
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The 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.
