Physical Sciences and Mathematics Commons^™

Fourier Acceleration In The Linear Sigma Model, Cameron Cianci

Honors Scholar Theses

The linear sigma model is a low energy effective model of Quantum Chromodynamics. This model mimics the breaking of chiral symmetry both spontaneously and explicitly through the quark condensate and pion mass matrix respectively. Fourier acceleration is a method that can be implemented in the Hybrid Monte-Carlo algorithm which decreases autocorrelations due to critical slowing down through tuning the mass parameters in the HMC algorithm. Fourier acceleration is applied to the linear sigma model with a novel mass estimation procedure, by assuming the modes behave approximately like simple harmonic oscillators. The masses are chosen by sampling the expectation values of …

Generation Of Phase Transitions Boundaries Via Convolutional Neural Networks, Christopher Alexis Ibarra

Open Access Theses & Dissertations

Accurate mapping of phase transitions boundaries is crucial in accurately modeling the equation of state of materials. The phase transitions can be structural (solid-solid) driven by temperature or pressure or a phase change like melting which defines the solid-liquid melt line. There exist many computational methods for evaluating the phase diagram at a particular point in temperature (T) and pressure (P). Most of these methods involve evaluation of a single (P,T) point at a time. The present work partially automates the search for phase boundaries lines utilizing a machine learning method based on convolutional neural networks and an efficient search …

Dual Energy Electron Storage Ring Cooler Design For Relativistic Ion Beams, Bhawin Dhital

Physics Theses & Dissertations

Collider experiments demand small beam emittances in order to achieve high luminosity. For light particles such as electrons, there exists a natural synchrotron radiation damping resulting in low emittance beams at equilibrium. In the case of heavy particle beams such as proton or ion beams, there is no significant synchrotron radiation damping effect and some cooling mechanism is needed to get to low emittance beams. A dual energy storage ring cooler is a novel concept proposed to cool hadron beams at higher energies. The design consists of two rings: a low energy ring and a high energy ring connected by …

A Mode-Sum Prescription For The Renormalized Stress Energy Tensor On Black Hole Spacetimes, Peter Taylor, Cormac Breen, Adrian Ottewill

Articles

In this paper, we describe an extremely efficient method for computing the renormalized stress-energy tensor of a quantum scalar field in spherically symmetric black hole spacetimes. The method applies to a scalar field with arbitrary field parameters. We demonstrate the utility of the method by computing the renormalized stress-energy tensor for a scalar field in the Schwarzschild black hole spacetime, applying our results to discuss the null energy condition and the semiclassical backreaction.

Classification Of Pixel Tracks To Improve Track Reconstruction From Proton-Proton Collisions, Kebur Fantahun, Jobin Joseph, Halle Purdom, Nibhrat Lohia

SMU Data Science Review

In this paper, machine learning techniques are used to reconstruct particle collision pathways. CERN (Conseil européen pour la recherche nucléaire) uses a massive underground particle collider, called the Large Hadron Collider or LHC, to produce particle collisions at extremely high speeds. There are several layers of detectors in the collider that track the pathways of particles as they collide. The data produced from collisions contains an extraneous amount of background noise, i.e., decays from known particle collisions produce fake signal. Particularly, in the first layer of the detector, the pixel tracker, there is an overwhelming amount of background noise that …

Search For A W' Boson Decaying To A Vector-Like Quark And A Top Or Bottom Quark In The All-Jets Final State At √S = 13 Tev, The Cms Collaboration

Department of Physics and Astronomy: Faculty Publications

A search is presented for a heavy W0 boson resonance decaying to a B or T vector-like quark and a t or a b quark, respectively. The analysis is performed using protonproton collisions collected with the CMS detector at the LHC. The data correspond to an integrated luminosity of 138 fb⁻¹ at a center-of-mass energy of 13TeV. Both decay channels result in a signature with a t quark, a Higgs or Z boson, and a b quark, each produced with a significant Lorentz boost. The all-hadronic decays of the Higgs or Z boson and of the t quark are …

Astrophysics, Cosmology And Particle Phenomenology At The Energy Frontier, Jorge Fernandez Soriano

Dissertations, Theses, and Capstone Projects

This dissertation consists of two parts, treating significantly separated fields. Each part consists on several chapters, each treating a somewhat isolated topic from the rest. In each chapter, I present some of the work developed during my passage through the graduate program, which has mostly been published elsewhere.

Part I – Cosmic Rays and Particle Physics

• Chapter 1: In this chapter we present an introduction to the topic of cosmic ray physics, with an special focus on the so-called ultra high energy cosmic rays: their potential origins, effects during their propagation between their sources and Earth, the different techniques used …

The Separation Of Charm And Bottom Decays Measured In P+Au Collisions At 200 Gev, Zhiyan Wang

Dissertations, Theses, and Capstone Projects

It has long been observed experimentally, from previous heavy-flavor electron measurements, that heavy quarks are subject to substantial modifications of their momentum spectrum. Using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), measurements of the production of open heavy flavor hadrons with charm and bottom quarks in p+Au collisions at 200 GeV are studied and presented in this thesis. Distance of closest approach analysis of electron tracks is used to study the semileptonic decay electrons from charm and bottom hadrons. The results include invariant yield and fraction of bottom electrons. In addition to the p+p and Au+Au collisions’ …

Magnetic Field Effects On The Physics Of Neutron Stars, Aric A. Hackebill

Dissertations, Theses, and Capstone Projects

In the context of neutron stars (NS), dense-magnetized quark and hadron models have been well studied under the assumption that the system's pressures are isotropic. However, the pressures determined from semi-classical statistical averaging of the energy momentum tensor in the presence of a uniform background magnetic field are anisotropic with different pressures arising along and perpendicular to the magnetic field direction. Since large magnetic fields are expected to be present in the interior of NS, it is important to understand the roll the pressure anisotropy plays. While considering the pressure anisotropy, we revisit some important calculations in NS physics.

We …

Investigation Of Holographic Lattice Theories, Muhammad Asaduzzaman

Dissertations - ALL

The Anti-de Sitter/Conformal Field theory (AdS/CFT) correspondence, also known as holography, has been the focus of a great deal of interest and research for the last two decades. It has improved our understanding of general relativity and quantum field theories simultaneously through the interplay between these two different kinds of theories. However, there are still many aspects of holography that we do not understand or demand further analysis. Perturbative quantum field theory and perturbative metric expansion techniques are not equipped to investigate holography in some of the most interesting regimes such as the strongly interacting gravitational theory in anti-de Sitter …

Plasmonic Nanomaterials-Based Point-Of-Care Biosensors, Rohit Gupta

McKelvey School of Engineering Theses & Dissertations

Point-of-care (POC) biosensors, although rapid and easy-to-use, are orders magnitude less sensitive than laboratory-based tests. Further they are plagued by poor stability of recognition element thus limiting its widespread applicability in resource-limited settings. Therefore, there is a critical need for realizing stable POC biosensors with sensitivity comparable to gold-standard laboratory-based tests. This challenge constitutes the fundamental basis of this dissertation work– to expand access to quality and accurate biodiagnostic tools. At the heart of these solutions lies plasmonic nanoparticles which exhibit unique optical properties which are attractive for label-free and labelled biosensors.Firstly, we improve the stability and applicability of label-free …

Qcd Corrections In Tqγ Production At Hadron Colliders, Nikolaos Kidonakis, Nodoka Yamanaka

Faculty Articles

We study QCD corrections for the associated production of a single top quark and a photon (tqγ production) at hadron colliders. We calculate the NLO cross section at LHC and future collider energies for a variety of kinematical cuts, and we estimate uncertainties from scale dependence and from parton distributions. We also calculate differential distributions in top-quark transverse-momentum and rapidity as well as photon energy. Finally, we study higher-order corrections from soft-gluon emission for this process, and we provide approximate NNLO (aNNLO) results for the cross section and top-quark differential distributions. We also compare our calculations with recent measurements from …

Improved Constraints On The Standard Model Higgs Self-Interaction Using A Search For Hh → 4b Via The Vector-Boson Fusion Production Mode At √S = 13 Tev In 126 Fb^-1 Of Data Collected By The Atlas Experiment, Christopher Milke

Physics Theses and Dissertations

A search for di-Higgs production via the Vector Boson Fusion mechanism decaying to 4 bottom quarks is performed using 126 fb−1 of data from Run 2 of ATLAS at √s = 13 TeV. The search was performed in the non-resonant regime, finding an upper bound on the production cross-section for the Standard Model VBF→HH→4b of about 200 times the Standard Model. Constraints are placed on both the HHVV coupling (which determines the W/Z-higgs four-point interaction strength) and HHH Higgs self-coupling scale factors at 95% confidence. The HHVV coupling scaling factor (κ2V ) is constrained to an observed interval between 0.09 …

Fermion-Induced Electroweak Symmetry Non-Restoration Via Temperature-Dependent Masses, Yu Hang Ng

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Standard Model (SM) and many extensions of SM predict that the electroweak (EW) symmetry was restored in the early universe when the temperature was around 160 GeV. However, recent studies showed that the interactions between some new scalars and SU(2)_L Higgs doublet(s) can cause the EW symmetry to remain broken at temperatures well above the EW scale in certain renormalizable extensions of SM. In this study, we found that new fermions from renormalizable models can also induce this EW symmetry non-restoration effect, provided that they have the appropriate temperature-dependent masses. These masses can arise naturally from the interactions between the …

Search For A Dark Leptophilic Scalar Produced In Association With Taupair In Electron-Positron Annihilation At Center-Of-Mass Energies Near 10.58 Gev., Diptaparna Biswas

Electronic Theses and Dissertations

Dark matter is believed to be a form of matter which seemingly accounts for approximately 85% of the matter in the universe and about 27% of its total mass–energy density. It doesn't participate in electromagnetic interaction, i.e. doesn't interact with light. Consequently, we cannot see it using optical or radio telescope and hence the name dark matter. However, it participates in gravitational interaction, and we hypothesize its existence based on a variety of astrophysical observations, including gravitational effects, that cannot be explained by the accepted theories of gravity unless we account for more matter than can be perceived through electromagnetic …

What Is A Photon? Foundations Of Quantum Field Theory, Charles G. Torre

All Physics Faculty Publications

This is a brief, informal, and relatively low-level course on the foundations of quantum field theory. The prerequisites are undergraduate courses in quantum mechanics and electromagnetism.

Introduction To Classical Field Theory, Charles G. Torre

All Complete Monographs

This is an introduction to classical field theory. Topics treated include: Klein-Gordon field, electromagnetic field, scalar electrodynamics, Dirac field, Yang-Mills field, gravitational field, Noether theorems relating symmetries and conservation laws, spontaneous symmetry breaking, Lagrangian and Hamiltonian formalisms.

Partial Automation Of Data Analysis In A Z Prime Boson Search, Ethan Colbert

Undergraduate Theses

Analysis of data from the ATLAS experiment at the LHC has been a research focus in the Department of Physics at Bellarmine University (BU). At BU, analysis has largely been focused on Z boson decays and searching for evidence of a Z’ (Z Prime) boson. The data are stored in the form of .xml files, with one file representing one collision event inside the ATLAS detector. Previous analyses have been conducted on an event-by-event basis, using the Hypatia software package. While this allows for high-quality visualization and effective event analysis, it is highly time-consuming. I propose and implement a piece …

A Performance Analysis Of The Belle Ii Detector, John Stacy

Honors Theses

The Belle II experiment has recently (2018) started data taking at the SuperKEKB electron-positron collider in Tsukuba, Japan. Detector performance studies are necessary to understand early data and prepare for more complex analyses. This study of the proton detection efficiency of the Belle II detector compares real and simulated data to find discrepancies with the intention to provide useful information for detector and calibration experts to better gauge detector performance. It also attempts to improve the characterization of proton identification efficiency at low momenta, which performs poorly under the current fitting model. This helps analysts exploring final states that include …

Lifetime Measurement Of The Xi_C^+ Using Belle Ii Monte Carlo, Paul Gebeline

Honors Theses

This analysis uses simulated data from the Belle II experiment to measure the lifetime of the Xi_c^+ baryon. Three different decay modes are investigated to explore the feasibility and accuracy of such measurements at Belle II. The Xi_c^+ lifetime is measured using one of these modes after reducing backgrounds from sources other than the decay of interest. The final result is 464 +/- 15 fs, which is consistent with the expected result of 442 fs within uncertainty. This result shows that Belle II can make competitive measurements of particle properties and decays.

Monte Carlo Study Of Lepton Flavor Universality Violation In B Decays With Belle Ii Simulation, Sakul Mahat

Honors Theses

Belle II, the first super B-Factory experiment, is designed to make precise measurements of weak interaction parameters and search for New Physics beyond the Standard Model of particle physics. The Standard Model of particle physics is a theory that classifies all known elementary particles and describes three of the four known fundamental forces in the universe. Physics beyond the Standard Model that addresses the theoretical developments needed to explain the deficiencies in the Standard Model is often referred to as New Physics. One of the assumptions of the Standard Model is that the couplings of particles that mediate the weak …

Measurement Of Neutrino-Induced Neutron Production In Lead, Brandon J. Becker

Doctoral Dissertations

The COHERENT Collaboration is an experimental effort to make the first measurement of coherent elastic neutrino-nucleus scattering (CE𝜈NS). The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory provides an intense, timed source of neutrinos from the decay of pions and muons produced during the spallation of mercury by 1 GeV protons generated in a particle accelerator. COHERENT seeks to make an unambiguous measurement by using a variety of low-threshold detectors capable of measuring the low-energy nuclear recoils resulting from CE𝜈NS interactions. This already challenging task is further complicated with the presence of backgrounds. Consequently, we must seek to reduce …

Development Of A Prototype Electron Detector For Use In Ucna+, Richard Mcdonald

Undergraduate Honors Theses

The UCNA Experiment at the Los Alamos Neutron Science Center (LANSCE) uses an electron spectrometer to observe angular correlations between the neutron spin and the momenta of β particles emitted during the process of β decay. These angular correlations give rise to an asymmetry determined by the ratio of two coupling constants, gA and gV . Combined with neutron lifetime measurements, these observations probe physics beyond the standard model through unitarity tests of the Cabbibo-Kobayashi-Maskawa Matrix. UCNA’s current spectrometer uses a multi-wire proportional chamber and a plastic scintillator coupled to four photomultiplier tubes (PMTs) by 2 meters of light guides …

Finite Dimensional Approximation And Pin(2)-Equivariant Property For Rarita-Schwinger-Seiberg-Witten Equations, Minh Lam Nguyen

Graduate Theses and Dissertations

The Rarita-Schwinger operator Q was initially proposed in the 1941 paper by Rarita and Schwinger to study wave functions of particles of spin 3/2, and there is a vast amount of physics literature on its properties. Roughly speaking, 3/2−spinors are spinor-valued 1-forms that also happen to be in the kernel of the Clifford multiplication. Let X be a simply connected Riemannian spin 4−manifold. Associated to a fixed spin structure on X, we define a Seiberg-Witten-like system of non-linear PDEs using Q and the Hodge-Dirac operator d∗ + d+ after suitable gauge-fixing. The moduli space of solutions M contains (3/2-spinors, purely …

Studies Of Bonus12 Radial Gem Detector And Tcs Beam Spin Asymmetry In Clas12, Jiwan Poudel

Physics Theses & Dissertations

The Barely Offshell Nucleon Structure (BONuS12) experiment adopted the concept of spectator tagging technique to study the nearly-free neutron structure function F2n in the CLAS12 of Jefferson Lab. A novel Radial Time Projection Chamber (RTPC) detector was built, tested and integrated into the CLAS12 system to detect a back-moving low momentum tagged proton in d(e, ep)X deep-inelastic scattering. It was a 40 cm long gaseous detector consisting of 3 layers of cylindrical GEM foils for the charge amplification, with the data readout directly from the surrounding padboard. The RTPC detected the recoiling spectator proton, in coincidence with …

Einstein's Equations, Lagrangians For General Relativity, And Adm Formalism, Timothy Corbett

Student Research Submissions

Einstein’s equations describe the relation of spacetime curvature and present matter. We will consider the case of a Lorentzian manifold diffeomorphic to ℝ × Σ, where time t ∈ ℝ and the three-dimensional manifold Σ represents space. In a homogeneous and isotropic universe, the three-dimensional manifold Σ of the Lorentzian manifold has Riemann curvature tensor ⁽³⁾R = KI, where K is a constant and I is the 3 × 3 identity matrix. Space is flat when K = 0, spherical when K is positive, and hyperbolic when K is negative. In this paper, we will show models agreeing with …

Using Z Boson Events To Study Parton-Medium Interactions In Pb-Pb Collisions, The Cms Collaboration, A. M. Sirunyan, A. Tumasyan, W. Adam, F. Ambrogi, T. Bergauer, Julie M. Hogan

Physics and Engineering Faculty Publications

The spectra measurements of charged hadrons produced in the shower of a parton originating in the same hard scattering with a leptonically decaying Z boson are reported in lead-lead nuclei (Pb-Pb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. Both Pb-Pb and pp data sets are recorded by the CMS experiment at the LHC and correspond to an integrated luminosity of 1.7 nb-1 and 320 pb-1, respectively. Hadronic collision data with one reconstructed Z boson candidate with the transverse momentum pT>30 GeV/c are analyzed. The Z boson constrains the initial energy and direction of the …

Search For Wγ Resonances In Proton-Proton Collisions At S=13 Tev Using Hadronic Decays Of Lorentz-Boosted W Bosons, The Cms Collaboration, A. Tumasyan, W. Adam, J. W. Andrejkovic, T. Bergauer, S. Chatterjee, Julie M. Hogan

Physics and Engineering Faculty Publications

A search for Wγ resonances in the mass range between 0.7 and 6.0 TeV is presented. The W boson is reconstructed via its hadronic decays, with the final-state products forming a single large-radius jet, owing to a high Lorentz boost of the W boson. The search is based on proton-proton collision data at s=13 TeV, corresponding to an integrated luminosity of 137 fb−1, collected with the CMS detector at the LHC in 2016–2018. The Wγ mass spectrum is parameterized with a smoothly falling background function and examined for the presence of resonance-like signals. No significant excess above the predicted background …

Erratum: Search For Heavy Higgs Bosons Decaying To A Top Quark Pair In Proton-Proton Collisions At S = 13 Tev (Journal Of High Energy Physics, (2020), 2020, 4, (171), 10.1007/Jhep04(2020)171), The Cms Collaboration, A. M. Sirunyan, A. Tumasyan, W. Adam, F. Ambrogi, T. Bergauer, Julie M. Hogan

Physics and Engineering Faculty Publications

In figure 7 of the original publication, the label of the y axis should have been (Formula presented.)”. The corrected version is shown in figure 1. Accordingly, the text pointing to the figure should read “figure 7 shows scans of (Formula presented.) for this hypothesis, as a function of the coupling modifier gAtt-”.

Measurement Of W±Γ Differential Cross Sections In Proton-Proton Collisions At S =13 Tev And Effective Field Theory Constraints, The Cms Collaboration, A. Tumasyan, W. Adam, J. W. Andrejkovic, T. Bergauer, S. Chatterjee, Julie M. Hogan

Physics and Engineering Faculty Publications

Differential cross section measurements of W±γ production in proton-proton collisions at s=13 TeV are presented. The data set used in this study was collected with the CMS detector at the CERN LHC in 2016-2018 with an integrated luminosity of 138 fb-1. Candidate events containing an electron or muon, a photon, and missing transverse momentum are selected. The measurements are compared with standard model predictions computed at next-to-leading and next-to-next-to-leading orders in perturbative quantum chromodynamics. Constraints on the presence of TeV-scale new physics affecting the WWγ vertex are determined within an effective field theory framework, focusing on the O3W operator. A …