Elementary Particles and Fields and String Theory Commons^™

Qcd Analysis Of Flavor-Nonchanging Hadronic Weak Processes Through Next-To-Leading Order, Girish Lingadahalli Muralidhara

Theses and Dissertations--Physics and Astronomy

Studies in quantum chromodynamics (QCD), the fundamental theory of the strong interactions, of low-energy hadronic weak processes utilize an effective Hamiltonian framework. Below the weak-mass scale, an effective Hamiltonian contains a series of Wilson coefficients and four-quark operators that come from the operator product expansion in the Standard Model. The effective hadronic Hamiltonian pertinent to a weak process is then obtained via a renormalization group analysis in QCD from the weak-mass scale to the low-energy scale of O(2 GeV). In this thesis, the construction and phenomenological implications of such an effective Hamiltonian for flavor-conserving, parity-violating quark processes in the Standard …

Symbolic Computation Of Squared Amplitudes In High Energy Physics With Machine Learning, Abdulhakim Alnuqaydan

Theses and Dissertations--Physics and Astronomy

The calculation of particle interaction squared amplitudes is a key step in the calculation of cross sections in high-energy physics. These complex calculations are currently performed using domain-specific symbolic algebra tools, where the computational time escalates rapidly with an increase in the number of loops and final state particles. This dissertation introduces an innovative approach: employing a transformer-based sequence-to-sequence model capable of accurately predicting squared amplitudes of Standard Model processes up to one-loop order when trained on symbolic sequence pairs. The primary objective of this work is to significantly reduce the computational time and, more importantly, develop a model that …

Beam Dynamics Simulations And Systematic Studies For The Muon G-2 Experiment At Fermilab, Abel M. Lorente Campos

Theses and Dissertations--Physics and Astronomy

The first results of the positive muon anomalous magnetic moment from the Muon g-2 Experiment at Fermilab differs from the Standard Model prediction by 3.3 standard deviations, with an experimental uncertainty of 0.46 ppm. Combining this result with the previous measurement from the Brookhaven National Laboratory, it sets the difference between experiment and theory at 4.2 standard deviations. The goal of the Muon g-2 Experiment at Fermilab is to increase this discrepancy to 5 standard deviations, which would require unprecedented precision in the measurements of 0.14 ppm. Of significant importance to achieving this precision, beam and spin dynamics simulations are …

Energy Integrated Ratio Analysis Of The Anomalous Precession Frequency In The Fermilab Muon G-2 Experiment, Ritwika Chakraborty

Theses and Dissertations--Physics and Astronomy

The muon’s anomalous magnetic moment, a_μ, provides a unique way for probing physics beyond the standard model experimentally as it gathers contributions from all the known and unknown forces and particles in nature. The theoretical prediction of a_μ has been in greater than 3 σ tension with the experimental measurement since the results of the Muon g-2 Experiment at the Brookhaven National Laboratory (E-821) were published in the early 2000s with a precision of 540 ppb. To settle this tension, the new Fermilab Muon g - 2 Experiment (E-989) is currently taking data with the aim of …

Neutron Spectroscopy Of The Parity-Violating 0.734 Ev Neutron Resonance In Lanthanum-139 In Preparation For The Noptrex Time Reversal Violation Experiment, Danielle Schaper

Theses and Dissertations--Physics and Astronomy

One of the most outstanding questions in physics is the matter-antimatter asymmetry of the Universe, resulting from excess baryogenesis processes during the early moments of the formation of the Universe. At present, the types of processes needed to explain this matter excess, so-called `CP-violating processes' are known to exist within the present framework of the Standard Model of particle physics. However, decades of research has shown that our understanding of the origin of these processes is incomplete, as we do not presently know of enough sources of CP-violating processes to account for the large baryon asymmetry that we observe. The …

Thermalization And Quantum Information In Conformal Field Theory, Ashish Kakkar

Theses and Dissertations--Physics and Astronomy

The consequences of the constraints of conformal symmetry are far-reaching within
theoretical physics. In this dissertation we address a series of questions in conformal
field theory: 1) We calculate the spectrum of qKdV charges in a large central charge
expansion. 2) We determine the corrections to bulk information geometry from 1/N
contributions to holographic correlators. 3) We study the higher genus partitions
functions of CFTs associated with classical and quantum error-correcting codes.

Data Acquisition, Analysis And Simulations For The Fermilab Muon G−2 Experiment, Fang Han

Theses and Dissertations--Physics and Astronomy

The goal of the new Muon g-2 E989 experiment at Fermi National Accelerator Laboratory (FNAL) is a precise measurement of the muon anomalous magnetic moment, a_μ ≡ (g-2)/2. The previous BNL experiment measured the anomaly a_μ(BNL) with an uncertainty of 0.54 parts per million (ppm). The discrepancy between the current standard model calculation of the a_μ(SM) and the previous measurement a_μ(BNL) is over 3σ. The FNAL Muon g-2 experiment aims at increasing the precision to 140 parts per billion (ppb) to resolve the discrepancy between the theoretical …

Effective Field Theory Applications: From Dark Matter To Neutrino Nucleon Scattering, Qing Chen

Theses and Dissertations--Physics and Astronomy

Weakly-interacting-massive-particles (WIMPs) are a large class of viable dark matter candidates. We compute cross sections for electroweak-doublet WIMPs scattering on atomic nuclei, at leading and subleading order using heavy WIMP effective field theory. Neutrino-nucleon charged current elastic scattering is an important process in the detectors of long baseline accelerator neutrino oscillation experiments. We compute QED radiative corrections to this process employing soft-collinear effective field theory.

Topics In Quantum Quench And Entanglement, Sinong Liu

Theses and Dissertations--Physics and Astronomy

The dissertation includes two parts.

In Part I, we study non-equilibrium phenomena in various models associated with global quantum quench. It is known that local quantities, when subjected to global quantum quench across or approaching critical points, exhibit a variety of universal scaling behaviors at various quench rates. To investigate if similar scaling holds for non-local quantities, we consider the scaling behavior of circuit complexity under quantum quench across the critical massless point in Majorana fermion field theory of the one-dimensional integrable transverse field Ising model and find it obeys such scaling. To investigate if similar scaling holds for non-relativistic …

Large N Fields And Holography, Animik Ghosh

Theses and Dissertations--Physics and Astronomy

We study (nearly) AdS/CFT holography within the context of the Sachdev-Ye- Kitaev (SYK) model. We present a systematic procedure to extract the dynamics of the low energy Schwarzian mode in SYK type models with a single energy scale J and emergent reparametrization symmetry in the infrared within the framework of perturbation theory. We develop a systematic approach using Feynman diagrams in bilocal theory to obtain a formal expression for the enhanced and O(1) corrections to the bilocal propagator and apply this general technique to large q SYK. We show that the Schwarzian theory describes a sector of a general class …

Sensitivity Of Electron-Proton Coincidence Asymmetries In Neutron Beta-Decay To Scalar And Tensor Interactions, Subash C. Nepal

Theses and Dissertations--Physics and Astronomy

We study the combined sensitivity of measurements of electron-proton coincidence asymmetries in polarized neutron beta-decay together with a measurement of the electron energy spectrum in unpolarized neutron beta-decay to beyond Standard Model (BSM) scalar and tensor interactions, via the appearance of such BSM physics in the Fierz interference terms b and b_v. Whereas measurements of the electron energy spectrum directly probe b, both the proton and neutrino asymmetries for which experimental results exist are not sensitive to b_v, but effectively to b - b_v. This results in reduced sensitivity to BSM scalar and …

Theoretical Studies Of C And Cp Violation In $\Eta \To \Pi^+ \Pi^- \Pi^0$ Decay, Jun Shi

Theses and Dissertations--Physics and Astronomy

A violation of mirror symmetry in the $\eta\to\pi^+\pi^-\pi^0$ Dalitz plot has long been recognized as a signal of C and CP violation. In this thesis, we show how the isospin of the underlying C- and CP-violating structures can be reconstructed from their kinematic representation in the Dalitz plot. Our analysis of the most recent experimental data reveals, for the first time, that the C- and CP-violating amplitude with total isospin I = 2 is much more severely suppressed than that with total isospin I = 0.

In searching for C- and CP-violating sources beyond the SM, we enumerate the leading-dimension, …

Η' Decay To Π+Π-Π+Π−, Ehsan Jafari

Theses and Dissertations--Physics and Astronomy

With the use of chiral theory of mesons [1], [2] we evaluate the decay rate of η′ → π⁺π⁻π⁺π⁻. Our theoretical study of this problem is different from the previous theo- retical study [3] and our predicted result is in a good agreement with the experiment. In this chiral theory we evaluate Feynman diagrams up to one loop and the decay rate is calculated with the use of triangle and box diagrams. The ρ⁰ meson includes in both type of diagrams as a resonance state. Divergent integrals in the loop calculations …

Disconnected-Sea Quarks Contribution To Nucleon Electromagnetic Form Factors, Raza Sabbir Sufian

Theses and Dissertations--Physics and Astronomy

We present comprehensive analysis of the light and strange disconnected-sea quarks contribution to the nucleon electric and magnetic form factors. The lattice QCD estimates of strange quark magnetic moment G^s_M (0) = −0.064(14)(09) μ_N and the mean squared charge radius ⟨r²_s⟩_E = −0.0043(16)(14) fm² are more precise than any existing experimental measurements and other lattice calculations. The lattice QCD calculation includes ensembles across several lattice volumes and lattice spacings with one of the ensembles at the physical pion mass. We have performed a simultaneous chiral, infinite volume, and continuum extrapolation in …

Neutron-Antineutron Transitions: Exploring B – L Violation With Quarks, Xinshuai Yan

Theses and Dissertations--Physics and Astronomy

In the Standard Model (SM), the quantity baryon number (B) − lepton number (L), B − L, is perfectly conserved. Therefore, the observation of B − L violation would reveal the existence of physics beyond the SM. Traditionally, given the severe experimental constraints on |∆B| = 1 processes, B − L violation with baryons is probed via neutron-antineutron (n − n̄) oscillations, although this process suffers from quenching in the presence of external fields or matter.

In this dissertation, we discuss another possibility, n − n̄ conversion, in which the |∆ …

Lattice Qcd Calculation Of The Momentum Fraction Carried By Quarks In The Nucleon, And The Roper Puzzle, Mingyang Sun

Theses and Dissertations--Physics and Astronomy

This thesis is concerned with the lattice QCD calculation of the momentum fraction carried by quarks in the nucleon. Particularly, the strange quark contribution, (x)_s, is calculated, as well as the ratio of the strange (x) to that of u/d in the disconnected insertion which will be useful in constraining the global fit of parton distribution functions at small x. The disconnected insertion is known to be hard to calculate on the lattice. We adopt the overlap fermion action on several 2 + 1 flavor domain-wall fermion ensembles with a light sea quark mass which corresponds to pion …

Universal Constraints On 2d Cfts And 3d Gravity, Joshua D. Qualls

Theses and Dissertations--Physics and Astronomy

We study constraints imposed on a general unitary two-dimensional conformal field theory by modular invariance. We begin with a review of previous bounds on the conformal dimension Delta₁ of the lowest primary operator assuming unitarity, a discrete spectrum, modular invariance, c_L, c_R > 1, and no extended chiral algebra. We then obtain bounds on the conformal dimensions Delta₂, Delta₃ using no additional assumptions. We also show that in order to find a bound for Delta₄ or higher Delta_n, we need to assume a larger minimum value for c_tot that grows …

The Dijet Cross Section Measurement In Proton-Proton Collisions At A Center Of Mass Energy Of 500 Gev At Star, Grant D. Webb

Theses and Dissertations--Physics and Astronomy

Polarized deep inelastic scattering experiments play a vital role in the exploration of the spin structure of the proton. The polarized proton-proton collider at RHIC provides direct access to the gluon spin distribution through longitudinal double spin asymmetry measurements of inclusive jets, pions, and dijets. This thesis presents the measurement of the dijet double differential cross-section in proton-proton collisions at center of mass energies of √s = 500 GeV. The data represent an integrated luminosity of 8.7 pb^-1 recorded by the STAR detector during the 2009 RHIC run. A comprehensive jet analysis was performed to determine the ideal …

Time Dependent Holography, Diptarka Das

Theses and Dissertations--Physics and Astronomy

One of the most important results emerging from string theory is the gauge gravity duality (AdS/CFT correspondence) which tells us that certain problems in particular gravitational backgrounds can be exactly mapped to a particular dual gauge theory a quantum theory very similar to the one explaining the interactions between fundamental subatomic particles. The chief merit of the duality is that a difficult problem in one theory can be mapped to a simpler and solvable problem in the other theory. The duality can be used both ways.

Most of the current theoretical framework is suited to study equilibrium systems, or …

Investigation Of Spin-Independent Cp Violation In Neutron And Nuclear Radiative Β Decays, Daheng He

Theses and Dissertations--Physics and Astronomy

CP violation is an important condition to explain the preponderance of baryons in our universe, yet the available CP violation in the Standard Model (SM) via the so-called Cabibbo-Kobayashi-Maskawa mechanism seems to not provide enough CP violation. Thus searching for new sources of CP violation is one of the central tasks of modern physics. In this thesis, we focus on a new possible source of CP violation which generates triple-product correlations in momenta which can appear in neutron and nuclear radiative β decay. We show that at low energies such a CP violating correlation may arise from the exotic coupling …

Gauge-Gravity Duality And Its Applications To Cosmology And Fluid Dynamics, Jae-Hyuk Oh

University of Kentucky Doctoral Dissertations

This thesis is devoted to the study of two important applications of gauge-gravity duality: the cosmological singularity problem and conformal fluid dynamics. Gauge-gravity duality is a concrete dual relationship between a gauge theory (such as electromagnetism, the theories of weak and strong interactions), and a theory of strings which contains gravity. The most concrete application of this duality is the AdS/CFT correspondence, where the theory containing gravity lives in the bulk of an asymptotically anti-de-Sitter space-time, while the dual gauge theory is a deformation of a conformal field theory which lives on the boundary of anti-de-Sitter space-time(AdS).

Our first application …