The spectra of predicted particles from elementary quark models (CQMs) are expansive, accurate for the low-lying spectra, but incomplete. The GlueX experiment at Jefferson Lab is a vehicle to study medium energy photoproduction of hadronic states. The primary goal of…
The spectra of predicted particles from elementary quark models (CQMs) are expansive, accurate for the low-lying spectra, but incomplete. The GlueX experiment at Jefferson Lab is a vehicle to study medium energy photoproduction of hadronic states. The primary goal of the GlueX collaboration is to study Quantum Chromodynamics (QCD, also known as the strong nuclear force) and the nature of quark confinement. The GlueX collaboration uses a polarized photon beam incident on a liquid hydrogen target (LH2) to investigate the aftermath of photon-proton interactions.The cascade baryons, denoted by Ξ, are defined by having two, second-generation, strange quarks with an additional first-generation light quark (u or d). Experimentally, few cascades have been discovered, which is the antithesis of what most models expect. The cascades have some favorable attributes but are difficult to detect because the production cross sections are small and direct production is unlikely. Fortunately, in the 12 GeV era of the GlueX experiment, there is sufficient energy, beam time and data analysis tools for the detection of excited cascade states and their properties.
From the reaction γp→K^+ K^+ Ξ^- π^0, the invariant mass spectra of Ξ^- π^0 system was surveyed for new possible resonances. The invariant mass spectrum has a strong Ξ(1530) signal with other smaller resonances throughout the spectrum. Preliminary cross sections for the Ξ(1530) that was photoproduced from the proton are presented at energies never before explored.
While the Ξ(1530) couples almost exclusively to the Ξπ channel, there is an easily identifiable Ξ(1690) signal decaying Ξπ. Through the use of a simultaneous fitting routing of the Ξ*- mass spectra, I was able to observe the Ξ(1690) decaying to the KΛ, as well as to the Ξ-π0 branch. With additional statistics, a measurement of the branching ratio should be possible.
Lastly, a partial wave analysis (PWA) was completed to verify that the total angular momentum of Ξ(1530) is J = 3/2 and consistent with having positive parity. Additionally, there is evidence of a potentially interesting feature slightly above the mass of the Ξ(1530) that should be more fully explored as new GlueX data becomes available.
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In thesis we will build up our operator theory for finite and infinite dimensional systems. We then prove that Heisenberg and Schrodinger representations are equivalent for systems with finite degrees of freedom. We will then make a case to switch…
In thesis we will build up our operator theory for finite and infinite dimensional systems. We then prove that Heisenberg and Schrodinger representations are equivalent for systems with finite degrees of freedom. We will then make a case to switch to a C*-algebra formulation of quantum mechanics as we will prove that the Schrodinger and Heisenberg pictures become inadequate to full describe systems with infinitely many degrees of freedom because of inequivalent representations. This becomes important as we shift from single particle systems to quantum field theory, statistical mechanics, and many other areas of study. The goal of this thesis is to introduce these mathematical topics rigorously and prove that they are necessary for further study in particle physics.
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Precision measurements of kinematic correlation parameters of free neutron decayserve as a powerful probe of the Standard Model of particle physics. A wide array
of Beyond the Standard Model physics theories can be probed by precision neutron
physics. The Nab experiment will…
Precision measurements of kinematic correlation parameters of free neutron decayserve as a powerful probe of the Standard Model of particle physics. A wide array
of Beyond the Standard Model physics theories can be probed by precision neutron
physics. The Nab experiment will measure a, the electron-neutrino correlation coefficient, and b, the Fierz interference term. a is amongst the most sensitive decay
parameters to λ = gA/gV , the ratio of the axial-vector and vector coupling constants
in the weak force. Two important systematic considerations for the Nab experiment
are average detector timing bias, which must be held to ≤ 0.3 ns, and energy calibration and linearity, which must be held to 1 part in 104
. Both systematics require an
in depth understanding of charge collection in Nab’s Si detectors. Simulation of Si
charge collection using numerical methods and the Shockley-Ramo Theorem has been
completed. A variety of detector tests, including detector and amplification electronics acceptance testing have also been completed. Also included in this dissertation is
my work with the Nab ultra-high vacuum and cryogenic system.
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Recent developments inspired by string theoretic considerations provide multiple maps between gravitational and non-gravitational degrees of freedom. In this dis- sertation I discuss aspects of three such dualities, the gauge/gravity duality and how it applies to condensed matter systems, the…
Recent developments inspired by string theoretic considerations provide multiple maps between gravitational and non-gravitational degrees of freedom. In this dis- sertation I discuss aspects of three such dualities, the gauge/gravity duality and how it applies to condensed matter systems, the fluid-gravity duality, and the color-kinematics duality.
The first of these, colloquially referred to as holography, in its simplest form posits a mapping of d-dimensional conformal field theory (boundary) partition functions onto d+1 dimensional gravitational(bulk) partition functions, where the space-time carries a negative cosmological constant. In this dissertation I discuss the results of our calculations examining the emergence of Fermi-surface like structures in the bulk spacetime despite the absence of explicit Fermions in the theory.Specifically the 4+1 dimensional Einstein-Maxwell-Chern-Simons theory with scalar degrees of freedom, with and without symmetry breaking is considered. These theories are gravity duals to spatially modulated gauge theories. The results of calculations presented here indicate the existence of a rich phase space, most prominently Fermi shells are seen.
The second set of dualities considered are the color-kinematic duality, also known as the double-copy paradigm and the fluid-gravity duality. The color-kinematic duality involves identifying spin-2 amplitudes as squares of spin-1 gauge amplitudes. This double copy picture is utilized to construct “single copy” representations for space- times where Einstein’s equations reduce to incompressible Navier-Stokes equations. In this dissertation I show how spacetimes that characterize irrotational fluids and constant vorticity fluids each map to distinct algebraically special spacetimes. The Maxwell fields obtained via the double-copy picture for such spacetimes further provide interesting parallels, for instance, the vorticity of the fluid is proportional to the magnetic field of the associated gauge field.
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The first numerical predictions of the dynamical diquark model of multiquark exotic hadrons are presented. Using Born-Oppenheimer potentials calculated from lattice QCD and phenomenological diquark(triquark) masses, mass eigenvalues that are degenerate in spin and isospin are computed from numerical solutions…
The first numerical predictions of the dynamical diquark model of multiquark exotic hadrons are presented. Using Born-Oppenheimer potentials calculated from lattice QCD and phenomenological diquark(triquark) masses, mass eigenvalues that are degenerate in spin and isospin are computed from numerical solutions to both coupled and uncoupled Schroedinger equations. Assuming reasonable estimates of the fine-structure splittings, we find that the band structure of our mass spectra agrees well with the experimentally observed spectrum of charmonium-like states. Using our best fits, we predict a number of unobserved states, such as pentaquark states that lie below the charmonium-plus-nucleon threshold.
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Starting with the dynamical picture of the exotic c[¯over c]-containing states XYZas the confinement-induced hadronization of a rapidly separating pair of a compact diquark and antidiquark, we describe the pentaquark candidates P[+ over c](4380)and P[+ over c](4450)in terms of a…
Starting with the dynamical picture of the exotic c[¯over c]-containing states XYZas the confinement-induced hadronization of a rapidly separating pair of a compact diquark and antidiquark, we describe the pentaquark candidates P[+ over c](4380)and P[+ over c](4450)in terms of a confined but rapidly separating color-antitriplet diquark cuand color-triplet “triquark” [¯ over c](ud). This separation explains the relatively small P[+ over c] widths, despite these 5-quark systems lying far above both the J/ψp and Ac [¯ over D](∗)0 thresholds. The P[+ over c] states are predicted to form isospin doublets with neutral partners P[0 over c].
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We study the exclusive double-photon annihilation processes, e+e- → γγ* → γV0 and e+e- → γ*γ* → V[0 over a]V[0 over b], where the V[0 over i] is a neutral vector meson produced in the forward kinematical region: s >>…
We study the exclusive double-photon annihilation processes, e+e- → γγ* → γV0 and e+e- → γ*γ* → V[0 over a]V[0 over b], where the V[0 over i] is a neutral vector meson produced in the forward kinematical region: s >> −t and −t >> A[2 over QCD]. We show how the differential cross sections [dσ over dt], as predicted by QCD, have additional falloff in the momentum transfer squared t due to the QCD compositeness of the hadrons, consistent with the leading-twist fixed-θCM scaling laws, both in terms of conventional Feynman diagrams and by using the AdS/QCD holographic model to obtain the results more transparently. However, even though they are exclusive channels and not associated with the conventional electron–positron annihilation process e+e- → γ* → q[bar over q], these total cross sections and σ(e+e- → γV0) and σ(e+e- → V[0 over a]V[0 over b]), integrated over the dominant forward- and backward-θCM angular domains, scale as 1/s, and thus contribute to the leading-twist scaling behavior of the ratio Re+e-. We generalize these results to exclusive double-electroweak vector-boson annihilation processes accompanied by the forward production of hadrons, such as e+e- → Z0V0 and e+e- → W-p+. These results can also be applied to the exclusive production of exotic hadrons such as tetraquarks, where the cross-section scaling behavior can reveal their multiquark nature.
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The OLYMPUS experiment measured the two-photon exchange contribution to elastic electron-proton scattering, over a range of four-momentum transfer from \(0.6 < Q^2 < 2.2\) \((\mathrm{GeV/c})^2\). The motivation for the experiment stemmed from measurements of the electric-to-magnetic form factor ratio…
The OLYMPUS experiment measured the two-photon exchange contribution to elastic electron-proton scattering, over a range of four-momentum transfer from \(0.6 < Q^2 < 2.2\) \((\mathrm{GeV/c})^2\). The motivation for the experiment stemmed from measurements of the electric-to-magnetic form factor ratio of the proton \(\mu G_E/G_M\) extracted from polarization observables in polarized electron-proton scattering. Polarized electron-proton scattering experiments have revealed a significant decrease in \(\mu G_E/G_M\) at large \(Q^2\), in contrast to previous measurements from unpolarized electron-proton scattering. The commonly accepted hypothesis is that the discrepancy in the form factor ratio is due to neglected higher-order terms in the elastic electron-proton scattering cross section, in particular the two-photon exchange amplitude.
The goal of OLYMPUS was to measure the two-photon exchange contribution by measuring the positron-proton to electron-proton elastic scattering cross section ratio, \(\sigma_{e^+p}/\sigma_{e^-p}\). The two-photon exchange contribution is correlated to the deviation of the cross section ratio from unity.
In 2012, the OLYMPUS experiment collected over 4 fb\(^{-1}\) of \(e^+p\) and \(e^-p\) scattering data using electron and positron beams incident on a hydrogen gas target. The scattered leptons and protons were measured exclusively with a large acceptance spectrometer. OLYMPUS observed a slight rise in \(\sigma_{e^+p}/\sigma_{e^-p}\) of at most 1-2\% over a \(Q^2\) range of \(0.6 < Q^2 < 2.2\) \((\mathrm{GeV/c})^2\). This work discusses the motivations, experiment, analysis method, and the preliminary results for the cross section ratio as measured by OLYMPUS.
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In the first part of this thesis, we use the generalized Landau-level represen-
tation to study the effect of screening on the properties of the graphene quantum Hall states with integer filling factors. The analysis is performed in the low-energy Dirac…
In the first part of this thesis, we use the generalized Landau-level represen-
tation to study the effect of screening on the properties of the graphene quantum Hall states with integer filling factors. The analysis is performed in the low-energy Dirac model in the mean-field approximation, in which the long-range Coulomb in- teraction is modified by the one-loop static screening effects. The solutions demon- strate that static screening leads to a substantial suppression of the gap parameters in the quantum Hall states with a broken U (4) flavor symmetry. The results of the temperature dependence of the energy gaps mimic well the temperature dependence of the activation energies measured in experiment. The Landau-level running of the quasiparticle dynamical parameters could be tested via optical studies of the integer quantum Hall states.
In the second part, by using the generalized Landau-level representation, we study the interaction induced chiral asymmetry in cold QED plasma beyond the weak-field approximation. The chiral shift and the parity-even chiral chemical potential function are obtained numerically and are found peaking near the Fermi surface and increases and decreases with the Landau level index, respectively. The results are used to quantify the chiral asymmetry of the Fermi surface in dense QED matter. The chiral asymmetry appears to be rather small even in the strongest mag- netic fields and at the highest stellar densities. However, the analogous asymmetry can be substantial in the case of dense quark matter.
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