Search for New Heavy Charged Bosons and Measurement of High-Mass Drell-Yan Production in Proton—Proton Collisions
Search for New Heavy Charged Bosons and Measurement of High-Mass Drell-Yan Production in Proton—Proton Collisions

Author: Markus Zinser

Publisher: Springer

Published: 2018-09-25

Total Pages: 386

ISBN-13: 3030006506

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This book presents two analyses, the first of which involves the search for a new heavy charged gauge boson, a so-called W' boson. This new gauge boson is predicted by some theories extending the Standard Model gauge group to solve some of its conceptual problems. Decays of the W' boson in final states with a lepton (l± = e± , μ±) and the corresponding (anti-)neutrino are considered. Data collected by the ATLAS experiment in 2015 at a center of mass energy of √s =13 TeV is used for the analysis. In turn, the second analysis presents a measurement of the double-differential cross section of the process pp->Z/gamma^* + X -> l^+l^- + X, including a gamma gamma induced contribution, at a center of mass energy of sqrt{s} = 8 TeV. The measurement is performed in an invariant mass region of 116 GeV to 1500 GeV as a function of invariant mass and absolute rapidity of the l^+l^-- pair, and as a function of invariant mass and pseudorapidity separation of the l^+l^-- pair. The data analyzed was recorded by the ATLAS experiment in 2012 and corresponds to an integrated luminosity of 20.3/fb. It is expected that the measured cross sections are sensitive to the PDFs at very high values of the Bjorken-x scaling variable, and to the photon structure of the proton.

Heavy Neutral Particle Decays to Tau Pairs
Heavy Neutral Particle Decays to Tau Pairs

Author: Michail Bachtis

Publisher: Springer Science & Business Media

Published: 2013-12-13

Total Pages: 161

ISBN-13: 3319032577

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The work presented in this thesis spans a wide range of experimental particle physics subjects, starting from level-1 trigger electronics to the final results of the search for Higgs boson decay and to tau lepton pairs. The thesis describes an innovative reconstruction algorithm for tau decays and details how it was instrumental in providing a measurement of Z decay to tau lepton pairs. The reliability of the analysis is fully established by this measurement before the Higgs boson decay to tau lepton pairs is considered. The work described here continues to serve as a model for analysing CMS Higgs to tau leptons measurements.

Extending the Limits in the Hunt for Long-lived Heavy Neutral Leptons with the ATLAS Experiment at the Large Hadron Collider at CERN
Extending the Limits in the Hunt for Long-lived Heavy Neutral Leptons with the ATLAS Experiment at the Large Hadron Collider at CERN

Author: Christian Appelt

Publisher:

Published: 2024*

Total Pages: 0

ISBN-13:

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Englische Version: A search for a long-lived, heavy neutral lepton ($\mathcal{N}$) in 139~fb$ {-1}$ of $\sqrt{s}=13$~TeV $pp$ collision data collected between 2015 and 2018 by the ATLAS detector at the Large Hadron Collider is presented. The $\mathcal{N}$ is assumed to be produced via $W \rightarrow \mathcal{N} \mu$ or $W \rightarrow \mathcal{N} e$ and decays into two charged leptons and a neutrino, forming a unique displaced vertex signature. A novel technique is used to reconstruct the $\mathcal{N}$ mass that discriminates between signal and background. No signal is observed, and limits are set on the squared mixing parameters of the $\mathcal{N}$ with the left-handed neutrino states for the $\mathcal{N}$ mass range $3$~GeV~$

Searches for Dijet Resonances
Searches for Dijet Resonances

Author: Lydia Audrey Beresford

Publisher: Springer

Published: 2018-12-14

Total Pages: 0

ISBN-13: 9783030073657

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This book addresses one of the most intriguing mysteries of our universe: the nature of dark matter. The results presented here mark a significant and substantial contribution to the search for new physics, in particular for new particles that couple to dark matter. The first analysis presented is a search for heavy new particles that decay into pairs of hadronic jets (dijets). This pioneering analysis explores unprecedented dijet invariant masses, reaching nearly 7 TeV, and sets constraints on several important new physics models. The two subsequent analyses focus on the difficult low dijet mass region, down to 200 GeV, and employ a novel technique to efficiently gather low-mass dijet events. The results of these analyses transcend the long-standing constraints on dark matter mediator particles set by several existing experiments.