Elementary Particles and Fields and String Theory Commons^™

Classification Of Topological Defects In Cosmological Models, Abigail Swanson

Student Research Submissions

In nature, symmetries play an extremely significant role. Understanding the symmetries of a system can tell us important information and help us make predictions. However, these symmetries can break and form a new type of symmetry in the system. Most notably, this occurs when the system goes through a phase transition. Sometimes, a symmetry can break and produce a tear, known as a topological defect, in the system. These defects cannot be removed through a continuous transformation and can have major consequences on the system as a whole. It is helpful to know what type of defect is produced when …

The Standard Model Precision Parameters At 200 Gev, Zamiul Alam

Graduate Research Theses & Dissertations

The Standard Model can be defined quantitatively by running parameters in a mass-independent renormalization scheme at a fixed reference scale. We provide a set of simple interpolation formulas that give the fundamental Lagrangian parameters in the MS-bar scheme at a renormalization scale of 200 GeV, safely above the top-quark mass and suitable for matching to candidate new physics models at very high mass scales using renormalization group equations. These interpolation formulas take as inputs the on-shell experimental quantities and use the best available calculations in the pure MS-bar scheme. They also serve as an accounting of the parametric uncertainties for …

A Search For New Physics In B(S) To Mu+Mu- Decays Using Multivariate Data Analysis, And Development Of Particle Detection Technology With Silicon Pixel Detectors, Aidan Grummer

Physics & Astronomy ETDs

A suite of linked research projects is undertaken, combining a search for phenomena beyond the Standard Model of particle physics, development of new instruments for greater precision in detecting fundamental particles, and tracking and understanding the effect upon the detectors of the radiation that is an indelible element of their operating environment. Data recorded by the ATLAS Detector at CERN are employed in a search for evidence of undiscovered particles contributing to the rate of decays of B⁰ and B⁰_s mesons to dimuon final states. New applications of machine learning techniques are implemented to separate this signal …

Using Heavy Flavors To Study New Physics, Kristopher Jason Healey

Wayne State University Dissertations

In this doctoral dissertation I discuss the possible standard model contributions to select leptonic heavy meson decay modes. Included are calculations of soft photon contributions to a di-lepton decay of B-mesons as well as two-particle hadronic unitary contributions to the rare di-leptonic decay of the neutral D meson. Additionally, constraints are calculated for two super-WIMP dark matter models from rare heavy flavor decays.

A Search For The Sm Higgs Boson In The Process Zhllbb In 4.1/Fb Of Cdf Ii Data, Shalhout Zaki Shalhout

Wayne State University Dissertations

This dissertation presents a search for the standard model (SM) Higgs boson in the associated production process ZH → l⁺l_- bb using 4.1fb^-1 of Tevatron collision data collected with the CDF II detector.

To increase the sensitivity to a ZH signal over previous CDF searches, we implement new electron and expanded b-jet identification algorithms.

We utilize neural network classifiers enhanced with matrix element probabilities, a b-jet identifying neural network, and multivariate jet energy corrections to maximize the separation of signal from SM backgrounds.

We employ three neural network classifiers separately optimized for each of our three …