Elementary Particles and Fields and String Theory Commons^™

A Study Of Systematic Uncertainties For A Photon-Like Low Energy Excess Search At Microboone, Gray Yarbrough

Doctoral Dissertations

The premise of this dissertation is the study of and reduction of systematic uncertainties in the MicroBooNE experiment at the Fermi National Accelerator Laboratory. MicroBooNE is a short-baseline oscillation experiment using the innovative liquid argon time projection chamber technology to study, with unprecedented detail, neutrino interactions. The primary goal of MicroBooNE is the investigation of the MiniBooNE low energy excess (LEE) of electron neutrino events, a result which raised fundamental questions on the existence of sterile neutrinos with broad implications to the field of particle physics. The principal study of this dissertation is a study of systematics as part of …

Calculation And Modeling Of The Neutron’S Magnetic Moment, Abhyuday Sharda

Masters Theses

This thesis presents the current state of neutron magnetic moment calcu- lations. It details the development of calculations through history. It also delves into an experiment measuring the neutron magnetic moment. It ex- plores other methods by which calculations can be improved to get a better/ more accurate number. The conclusion is that there are still a lot of areas unexplored in context of the calculation of neutron magnetic moment and areas relevant to be worked upon are detailed.

Analysis Of Possible Hybrid Meson Decay, Jasper Bergh

Honors Theses

This research looked at data from the GlueX experiment at the Thomas Jefferson National Accelerator Facility to search for evidence of the π1(1600) particle, an exotic hybrid meson, decaying to an eta' and π0. We specifically looked into decays of the eta' to an eta, π+, and π-, with the eta decaying to 3 πo's. We successfully reconstructed an eta from the 3 πo's, and an eta' from the eta, π+, and π-. However, we did not observe the π1(1600), but, a 6:1 ratio of signal to background in the eta' mass. With more statistics this would be a viable …

Beyond The Standard Models Of Particle Physics And Cosmology, Gabriele Rigo

Dissertations - ALL

Despite their numerous successes both from the theoretical and experimental point of view, conceptual and observational evidence suggests the Standard Models of Particle Physics and Cosmology should be considered incomplete theories, reliable only within their well-defined regime of validity. This dissertation covers various possible extensions of those models from the theoretical, phenomenological and model-building perspective. The topics analyzed range from extra-dimensional approaches to the hierarchy problem, to the AdS/CFT description of perturbative anomaly inflow, and new probes of vacuum energy in neutron stars and gravitational waves.

Field Theories From Physical Requirements: Noether's First Theorem, Energy-Momentum Tensors And The Question Of Uniqueness, Mark Robert Baker

Electronic Thesis and Dissertation Repository

An axiomatic approach to physics is proposed for obtaining classical gauge theories from a common set of physical requirements based on standard features of special relativistic field theories such as gauge invariance, conformal invariance and being in four dimensions. This approach involves the use of Noether's first theorem to directly obtain a unique, complete set of equations from the symmetries of the action. However, implementation of this procedure is obstructed by issues of ambiguity and non-uniqueness associated with the conserved tensors in the majority of special relativistic field theories. In the introductory chapter, we outline the three major problems which …

Model Of Electromagnetic Waves In An Axion-Induced Parity Symmetry Violation, Sarah Lipstone

Macalester Journal of Physics and Astronomy

Axion particles have been postulated to resolve the strong CP problem in Quantum chromodynamics. The axion field may double as the inflaton field that produces cosmic inflation. In this project, we use a combination of analytical and numerical analysis to study how axion-induced parity symmetry violation affects the dynamics of electromagnetic waves.

Towards Neutron Transformation Searches, Joshua L. Barrow

Doctoral Dissertations

To probe the origins of the baryon asymmetry, baryon number violation, the last unconfirmed Sakharov condition, must be definitively observed experimentally. Similarly, the nature of dark matter is currently unknown, and calls out for new candidates to be investigated. Each of these issues can be considered through the study of neutron transformations.

Some rare baryon number violating processes, such as neutron-antineutron transformations, are expected to probe baryogenesis. Here, I show progress on this discovery target through construction of more accurate Monte Carlo models, the design of future detectors, creation of more complete atmospheric neutrino background simulations, and use of automated …

Measuring Electron Diffusion And Constraining The Neutral Current Π0 Background For Single-Photon Events In Microboone, Andrew Mogan

Doctoral Dissertations

Liquid Argon Time Projection Chambers (LArTPCs) are a rising technology in the field of experimental neutrino physics. LArTPCs use ionization electrons and scintillation light to reconstruct neutrino interactions with exceptional calorimetric and position resolution capabilities. Here, I present two analyses conducted in the MicroBooNE LArTPC at Fermilab: a measurement of the longitudinal electron diffusion coefficient, DL, in the MicroBooNE detector and a constraint of the systematic uncertainty on MicroBooNE's single-photon analysis due to the dominant neutral current (NC) π0 background. Longitudinal electron diffusion modifies the spatial and timing resolution of the detector, and measuring it will help correct for these …

Software Validation And Data Quality Monitoring Of The Klm Detector At Belle Ii., Dustyn Hofer

College of Arts & Sciences Senior Honors Theses

The Belle II Experiment at the SuperKEKB collider in Tsukuba, Japan is the latest of a new generation of B-factory experiments, designed to produce B meson particles in abundance. The aim of the Belle II experiment is to "discover new physics in the decay of the bottom quark (b), charm quark (c) and tau lepton (τ) and explore the dark sector." The SuperKEKB collider aims to produce instantaneous luminosities of upwards of 8 × 1035 cm−2 s−1, nearly an order of magnitude higher than previous B- factory experiments Belle and BABAR. Software packages, such as physics modules for the popular …

Detecting The Phi Meson With Clas12, Paul Simmerling

Honors Scholar Theses

Analysis and detection of the phi(1020) vector meson from exclusive electroproduction decay into Kaons have been performed. Studying exclusive phi electroproduction is an ideal channel for quantifying the gluonic properties of the nucleon. This detection used the CEBAF Large Acceptance Spectrometer (CLAS12) at Thomas Jefferson National Accelerator Facility (JLab) with a 10.6 GeV longitudinally polarized electron beam and an unpolarized hydrogen target. Using the detected final state particles phase space, x_B, Q^2, W, and by developing specialized exclusivity cuts as well as several additional cuts, events containing the production of a phi(1020) meson were able to be extracted. Additionally, a …

Curved Spacetime In The Causal Set Approach To Quantum Gravity, Ayush Dhital

Honors Theses

Causal Set theory is an approach to quantum gravity. In this approach, the spacetime continuum is assumed to be discrete rather than continuous. The discrete points in a causal set can be seen as a continuum spacetime if they can be embedded in a manifold such that the causal structure is preserved. In this regard, a manifold can be constructed by embedding a causal set preserving causal information between the neighboring points. In this thesis, some of the fundamental properties of causal sets are discussed and the curvature and dimension information of Minkowski, de Sitter, and Anti-de Sitter spaces is …

Study Of Neutral Hadron Production In A High Intensity Particle Physics Experiment., Jake W. Berg

Electronic Theses and Dissertations

In this dissertation I present independent measurements of the multiplicities, R, of π⁰ and η mesons produced in annihilation interactions of electrons and positrons at a center-of-mass energy of 10.54 GeV. Data were collected using the BaBar detector at the PEP-II storage rings located at the SLAC National Accelerator Laboratory in Menlo Park, California. Both mesons have a decay mode to two photons, which is used to identify them and measure their production per event. I find R(π⁰) = 2.8±0.3 per event and R(η) = 0.25±0.03 per event. I also present my contributions to …

Composite Gravity In Curved Spacetime, Austin Batz

Undergraduate Honors Theses

This work presents the development of a quantum theory of gravity motivated by diffeomorphism-invariance and background-independence. A composite graviton state that satisfies the linearized Einstein’s field equations has been identified via perturbative expansion about a curved vacuum spacetime. The emergence of this gravitational interaction is discussed, as well as cancellation of tadpoles and treatment of ultraviolet divergences via dimensional regularization. In other words, the formalism of quantum field theory is used to identify a gravitational interaction as an emergent phenomenon rather than as a fundamental aspect of nature. The lattice is proposed as a candidate for a physical regulator, and …

Exploring Manifoldlike Causal Sets And Their Dimensions, Santosh Bhandari

Honors Theses

Causal Set Theory is an approach to quantum gravity that tries to replace the continuum spacetime structure of general relativity with the spacetime that has the property of discreteness and causality. From the standpoint of causal set theory, our spacetime is made up of discrete points that are causally related to one another. A causal set is said to be manifoldlike if it can be faithfully embedded in a Lorentzian manifold. In this thesis, some of the fundamental properties of causal sets are discussed. The first chapter is devoted to the historical background of quantum gravity with a discussion of …

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 …

Geometrization Of Hawking Radiation Via Ricci Flow, Alexander Cassem

Ramaley Celebration

In 1982, Richard S. Hamilton formulated Ricci flow along manifolds of three dimensions of positive Ricci curvature as an attempt to resolve Poincaré’s Conjecture. However, it took until 2006 by Grigori Perelman to resolve the conjecture with Ricci flow. Since then, research in pure mathematics on Ricci Flow increased exponentially, and people began to apply it towards physics. For example, Ricci flow has been found to be the Renormalization Group flow of the bosonic string and sigma model. However, Ricci flow’s analogous counterpart being the heat equation, makes it appear to have more applications. For this reason, we have studied …

A Search For New Resonances Decaying Into A Weak Vector Boson And A Higgs Boson In Hadronic Final States With The Atlas Detector At The Large Hadron Collider, Zachary Alden Meadows

Doctoral Dissertations

A search for heavy resonances decaying to a $W$ or $Z$ boson and a Higgs boson in the final state is described. The search uses $139\ \mathrm{fb}^{-1}$ of proton-proton collision data at $\sqrt{s} = 13$ TeV collected by the ATLAS detector at the CERN Large Hadron Collider from 2015 to 2018. The results are presented in terms of constraints on a simplified model with a heavy vector triplet. Upper limits are set on the production cross-section times branching fraction for resonances decaying into a W/Z boson and a Higgs boson in the mass range between 1.2 to 5 TeV.

Exploring Qcd Factorization At Moderate Energy Scales, Eric Alan Moffat

Physics Theses & Dissertations

Asymptotic freedom in QCD facilitates the use of partonic degrees of freedom over short distances, but physical processes are sensitive to a wide range of scales. Thus, it is necessary in QCD calculations to utilize a factorization scheme to separate a process into perturbative and non-perturbative factors. This separation relies on an assumption that one energy scale is infinitely larger than the other scales involved in the process. However, much experimental research in areas such as nucleon structure and quark-hadron duality occur at more moderate energy scales where that basic assumption may not be true but perturbative calculations should still …

Copper Clusters: Study Of Geometric Structure Using Computer Simulation, Nodirbek Ikromjonovich Ibrokhimov

Karakalpak Scientific Journal

In this work, we investigated the geometric structure of small neutral copper clusters with low energy using the MD (Molecular Dynamics) method. When calculating the processes of interatomic interaction, we used a potential EAM (Embedded-atom method). A computer model of Cu_n (n = 2-13) clusters has been created. The geometric shapes of the Cu₂, Cu₃, Cu₄, Cu₅, Cu₆, Cu₇, Cu₈, Cu₉, Cu₁₀, Cu₁₁, Cu₁₂, and Cu₁₃ clusters have been studied and the structural parameters (Cu-Cu bond …

Lorentz Violation In Neutrino Interactions, Pranav Jayaram Seetharaman

Physics

Both the Standard Model of particle physics and General Relativity require Lorentz symmetry as a fundamental building block. In this paper, we learn about a framework called the Standard Model Extension that allows us to determine how physical phenomenon would change if we deviated from Lorentz invariance in the Standard Model and General Relativity. We use the Standard Model Extension to analyze a specific high-energy, astrophysical neutrino interaction that is only possible if Lorentz symmetry can be broken. The interaction we look at is the decay of a neutrino into an electron-positron pair, which is not possible in conventional physics. …