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Articles 1 - 30 of 43
Full-Text Articles in Physics
A Valence-Bond Operator Algebra For Quantum Spin Models And Its Applications, Huu Tran Do
A Valence-Bond Operator Algebra For Quantum Spin Models And Its Applications, Huu Tran Do
Electronic Theses and Dissertations
The Heisenberg Hamiltonian is the prototype model for quantum magnetism. The Hamilto- nian includes exchange couplings between vector spins, which are the intrinsic magnetic moments of localized electrons. The classical energy between any pair of interacting spins can be minimized by aligning them parallel (ferromagnetic case) or antiparallel (antiferromagnetic), depending on the sign of the coupling. But quantum fluctuations play a key role, and a full quantum mechanical treatment of the many-body system is generally required. Finding the exact ground-state energy and wave function of isotropic antiferromagnetic (AFM) systems for an arbitrary spin-S and lattice morphology is still a challenging …
Search For Cpt And Lorentz Invariance Violation In The Muon G-2 Experiment At Fermilab, Meghna Bhattacharya
Search For Cpt And Lorentz Invariance Violation In The Muon G-2 Experiment At Fermilab, Meghna Bhattacharya
Electronic Theses and Dissertations
The Muon g-2 experiment at Fermilab (E989) aims to measure the anomalous magnetic moment of the muon, $a_{\mu}= (g-2)/2$, to a groundbreaking precision of $140$ ppb, obtaining a near four-fold increase in precision over the previous experiment, E821, at the Brookhaven National Laboratory (BNL). The value of $a_{\mu}$ from BNL currently differs from the Standard Model prediction by $\sim 3.7$ standard deviations, suggesting the potential for new physics and therefore, motivating a new experiment.Because the theory predicts this number with high precision, testing the g-factor through experiment provides a stringent test of the SM and can suggest physics beyond the …
Dynamics For Discretized Gravity In The Causal Set Approach, Benjamin Pilgrim
Dynamics For Discretized Gravity In The Causal Set Approach, Benjamin Pilgrim
Electronic Theses and Dissertations
Causal set theory is an approach to quantum gravity which replaces the continuous spacetime manifold with a discrete set of points and a partial order. In this work, I will focus on causal sets embeddable in two-dimensional manifolds, and define an action based on chains which in the continuum limit replicates the Einstein-Hilbert action; furthermore, I will propose a variational principle based on this action and numerically show it can distinguish nonflat manifoldlike causal sets from the most common type of nonmanifoldlike causal sets. I will then supplement this action with a boundary term similar to the Gibbons-Hawking-York boundary term …
Geographic Variations Of Sound Channel Axis In The Global Ocean, Mukunda Kumar Acharya
Geographic Variations Of Sound Channel Axis In The Global Ocean, Mukunda Kumar Acharya
Electronic Theses and Dissertations
Sound signals are used for imaging and communication in the ocean. Underwater sound speed has a minimum at a certain depth that forms a sound channel for long-range underwater sound propagation. The geographic variation of sound channel is crucial in uses of underwater sound in various environments including ocean acoustic tomography and monitoring of global warming. In this work, sound speed and depth of the channel axis in the global ocean are characterized for their variation with the latitude, longitude, and depth.
Gravitational Radiation From Superradiant Instabilities Of Rotating Black Holes, Shrobana Ghosh
Gravitational Radiation From Superradiant Instabilities Of Rotating Black Holes, Shrobana Ghosh
Electronic Theses and Dissertations
We use the Teukolsky formalism to calculate the gravitational radiation from a non-axi\-symmetric cloud formed due to superradiant amplification of a spin-0 bosonic field. We focus on the prospects of the future space-based gravitational wave detector, Laser Interferometer Space Antenna (LISA), and the current version of ground-based detector, Advanced Laser Interferometer Gravitational-Wave Observatory (AdLIGO), to detect or constrain scalars with mass in the range $m_s\in [10^{-19},10^{-15}]$ eV and $m_s\in[10^{-14},10^{-11}]$ eV, respectively. Using astrophysical models of black hole populations calibrated to observations we find that, in optimistic scenarios, AdLIGO could detect up to $10^4$ resolvable events in a four-year search if …
Manifoldlike Causal Sets, Miremad Aghili
Manifoldlike Causal Sets, Miremad Aghili
Electronic Theses and Dissertations
The content of this dissertation is written in a way to answer the important question of manifold likeness of causal sets. This problem has importance in the sense that in the continuum limit and in the case one finds a formalism for the sum over histories, the result requires to be embeddable in a manifold to be able to reproduce General Relativity. In what follows I will use the distribution of path length in a causal set to assign a measure for manifold likeness of causal sets to eliminate the dominance of nonmanifold like causal sets. The distribution of interval …
Acoustic Radiation Force On A Fluid To Fluid Boundary By Phase Plate Focused Ultrasound, Robert Lee Lirette
Acoustic Radiation Force On A Fluid To Fluid Boundary By Phase Plate Focused Ultrasound, Robert Lee Lirette
Electronic Theses and Dissertations
In this study, the physics and applications of the ultrasonic radiation force at the interface between two immiscible fluids were investigated. These studies were performed using low-profile discrete-stepped lenses to the modify the phase of the incident radiation generating multiple field morphologies. In its first application to acoustics, a fraxicon lens was developed to approximate the field generated by an axicon. This type of lens creates a minimally diffractive Bessel beam and long depth of focus that is useful in ultrasonic imaging, therapy, and non-destructive evaluation techniques. Fields modified by fraxicon, Fresnel, and axicon lenses were characterized experimentally by scanning …
Investigation Of Narrow Bipolar Events In Mississippi Thunderstorms, Sampath Asiri Bandara
Investigation Of Narrow Bipolar Events In Mississippi Thunderstorms, Sampath Asiri Bandara
Electronic Theses and Dissertations
In the first part of the study FA and Log-RF data were used to examine low-altitude (<8.0 km) negative NBEs (NNBEs) to see how many -CG flashes were initiated by NNBEs. Out of 686 -CG flashes only 33 (5%) flashes were initiated by an NNBE. These NNBEs occurred at an average altitude of 6.2 km had average amplitude (range-normalized amplitude to 100 km) of 0.4 V/m and had average VHF (Log-RF) power of 130 W. Since the low-altitude NNBEs were substantially weaker than positive NBEs that initiate intracloud (IC) flashes it is hypothesized that -CG flashes are easier to initiate than IC flashes. The second part of the study investigated the properties of 201 positive NBEs (+NBEs). The +NBEs were classified in two ways: into Types A-D [Karunarathne et al. 2015] and into three different groups: Isolated Not-isolated and IC flash-initiator or INBE [Wu et al. 2014]. The average VHF (Log-RF) power of NBEs within the A-D categories were 1.9 4 9.8 and 13.2 kW respectively while the powers for the Isolated Not-isolated and INBE categories were 10.1 4 and 10.1 kW respectively. The third study considered 34 NBEs that occurred close in space and time to each other: 13 pairs of NBEs one group of three +NBEs and one group of five +NBEs. The NBEs were overlaid on radar data of the parent thunderstorms. The data indicate that the individual NBEs in each group initiated in separate intense electric field regions of small extent rather than in a single large-scale electric field region. This dissertation investigates Narrow Bipolar Events (NBEs) which are a type of short-duration (10- 30 µs) lightning discharge. The study primarily used data from NBEs collected in 2016 at seven sensor sites within 50 km of Oxford Mississippi USA. Each sensor site had three electromagnetic antennas called Fast Antenna (FA) dE⁄dt and Log-RF with bandwidths of 0-2.5 MHz 0-1.0 MHz and 186-192 MHz respectively. NBEs are often isolated from other lightning events in thunderclouds but they sometimes initiate negative cloud-to-ground (-CG) and intracloud (IC) lightning flashes or they can occur during these flashes.
Experimental Investigation Of Impurities And Their Effect On Acousto-Electric Properties Of Lithium Niobate, Chandrima Chatterjee
Experimental Investigation Of Impurities And Their Effect On Acousto-Electric Properties Of Lithium Niobate, Chandrima Chatterjee
Electronic Theses and Dissertations
No abstract provided.
The Beam Dynamics And Beam Related Uncertainties In Fermilab Muon G-2 Experiment, Wanwei Wu
The Beam Dynamics And Beam Related Uncertainties In Fermilab Muon G-2 Experiment, Wanwei Wu
Electronic Theses and Dissertations
The anomaly of the muon magnetic moment, aμ ≡ (g-2)/2, has played an important role in constraining physics beyond the Standard Model for many years. Currently, the Standard Model prediction for aμ is accurate to 0.42 parts per million (ppm). The most recent muon g-2 experiment was done at Brookhaven National Laboratory (BNL) and determined aμ to 0.54 ppm, with a central value that differs from the Standard Model prediction by 3.3-3.6 standard deviations and provides a strong hint of new physics. The Fermilab Muon g-2 Experiment has a goal to measure aμ to unprecedented precision: 0.14 ppm, which could …
Final Muon Cooling For A Muon Collider, John Gabriel Acosta Castillo
Final Muon Cooling For A Muon Collider, John Gabriel Acosta Castillo
Electronic Theses and Dissertations
To explore the new energy frontier, a new generation of particle accelerators is needed. Muon colliders are a promising alternative if muon cooling can be made to work. Muons are 200 times heavier than electrons, so they produce less synchrotron radiation, and they behave like point particles. However, they have a short lifetime of 2.2 μs and the beam is more difficult to cool than an electron beam. The Muon Accelerator Program (MAP) was created to develop concepts and technologies required by a muon collider. An important effort has been made in the program to design and optimize a muon …
Effective Interactions Between Local Hopping Modulations On The Square Lattice, Huu T. Do
Effective Interactions Between Local Hopping Modulations On The Square Lattice, Huu T. Do
Electronic Theses and Dissertations
No abstract provided.
Compact Objects In Relativistic Theories Of Gravity, Hector Okada Da Silva
Compact Objects In Relativistic Theories Of Gravity, Hector Okada Da Silva
Electronic Theses and Dissertations
In this dissertation we discuss several aspects of compact objects, i.e. neutron stars and black holes, in relativistic theories of gravity. We start by studying the role of nuclear physics (encoded in the so-called equation of state) in determining the properties of neutron stars in general relativity. We show that low-mass neutron stars are potentially useful astrophysical laboratories that can be used to constrain the properties of the equation of state. More specifically, we show that various bulk properties of these objects, such as their quadrupole moment and tidal deformability, are tightly correlated. Next, we develop a formalism that aims …
Low-Frequency Emission Enhancement By Resonant Acoustic Metamaterials, Maryam Landi
Low-Frequency Emission Enhancement By Resonant Acoustic Metamaterials, Maryam Landi
Electronic Theses and Dissertations
Omnidirectional and directional acoustic emission enhancements, at low frequencies as well as broad frequency bands, are highly demanded in audio, medical ultrasonics, and underwater acoustics. Emission enhancement and controlling the directivity of an acoustic source is however restricted to the properties of the source. In particular, the size of the source, in comparison with the wavelength of the sound, plays a very dominant role in determining the quality of the emitted acoustic wave. Most problems arise when there is a small acoustic source emitting very low frequency sound with large wavelength. Prior studies have proposed several solutions to this problem …
Design Of A High Luminosity 100 Tev Proton Antiproton Collider, Sandra Jimena Oliveros Tautiva
Design Of A High Luminosity 100 Tev Proton Antiproton Collider, Sandra Jimena Oliveros Tautiva
Electronic Theses and Dissertations
Currently new physics is being explored with the Large Hadron Collider at CERN and with Intensity Frontier programs at Fermilab and KEK. The energy scale for new physics is known to be in the multi-TeV range, signaling the need for a future collider which well surpasses this energy scale. A 10 34 cm-2 s-1 luminosity 100 TeV proton-antiproton collider is explored with 7× the energy of the LHC. The dipoles are 4.5 T to reduce cost. A proton-antiproton collider is selected as a future machine for several reasons. The cross section for many high mass states is 10 times higher …
A Thermal Enclosure Prototype For A Suspended Inertial Sensor, Mohammad Afrough
A Thermal Enclosure Prototype For A Suspended Inertial Sensor, Mohammad Afrough
Electronic Theses and Dissertations
Although Ligo has detected six gravitational waves so far, people are still conducting research to improve the sensitivity of the detectors in different aspects. At low frequency band, one of the main sources of noise is seismic vibration. Lowering the noise level in this band, helps us to follow the coalescence of compact binary systems earlier in their transformation and increase the signal-to-noise ratio. It also allows us to detect merger of more massive objects. Hence, an isolation system is required to reduce the seismic noise. As a part of isolation system (which can be a passive or an active …
Searching For New Physics In The B-Quark’S And Higgs’ Sectors Via Kinematic And Angular Distributions, Shanmuka Shivashankara
Searching For New Physics In The B-Quark’S And Higgs’ Sectors Via Kinematic And Angular Distributions, Shanmuka Shivashankara
Electronic Theses and Dissertations
The kinematic and angular distributions are calculated for the decay Λ b → Λclν l. Deviations from the standard model are expected given the apparent lepton flavor violation in the process B → D(*)+ τ – ντ. Including these measured deviations from the SM, the upper and lower bounds for R Λb = B(Λ b → Λcτ ντ) / B(Λ b → Λcl νl) are calculated along with other observables for a variety of new physics Lorentz structures. Distributions are also calculated for H → W –W+*(or H +*) → τ–ν ττ+ντ via Type II and leptophilic 2HDM’s. Although, the …
Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study, Sumudu Tennakoon
Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study, Sumudu Tennakoon
Electronic Theses and Dissertations
Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with a composition near morphotropic phase boundary (MPB) was investigated using a resonant ultrasound spectroscopy (RUS) methodologies in the temperature range of 293 K - 800 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic …
Computation Of Acoustic Ressure Fields Produced In Feline Brain By High-Intensity Focused Ultrasound, Nazanin Omidi
Computation Of Acoustic Ressure Fields Produced In Feline Brain By High-Intensity Focused Ultrasound, Nazanin Omidi
Electronic Theses and Dissertations
In 1975, Dunn et al. (Jasa 58:512-514) shothat a simple relation describes the ultrasonic threshold for cavitation induced changes in the mammalian brain. The thresholds for tissue damage were estimated for a variety of acoustic parameters in exposed feline brain. The goal of this study was to improve the estimates for acoustic pressures and intensities present in vivo during those experimental exposures by estimating them using nonlinear rather than linear theory. In our current project, the acoustic pressure waveforms produced in the brains of anesthetized felines were numerically simulated for a spherically focused, nominally f1-transducer (focal length = 13 cm) …
Fscan Code Development For Advanced Ligo Detector Characterization, Cody Arceneaux
Fscan Code Development For Advanced Ligo Detector Characterization, Cody Arceneaux
Electronic Theses and Dissertations
The Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) is an experiment designed to provide direct detection of gravitational waves. Its searches for periodic gravitational waves are highly susceptible to long-duration noise that appears as spectral lines. FScan is a tool for finding spectral lines and is used to identify the lines that appear in the gravitational-wave data; it is also used to characterize LIGO's detectors. This thesis details work in rewriting the plotting portion of FScan, making improvements to the FScan driver script, and writing code to assist in the tracking of wandering spectral lines. In particular, this thesis presents the …
Testing Lepton Nonuniversality In Tau Neutrino Scattering, Hongkai Liu
Testing Lepton Nonuniversality In Tau Neutrino Scattering, Hongkai Liu
Electronic Theses and Dissertations
Recently hints of lepton flavor non-universality emerged in the BaBar and LHCb experiments. In this paper we propose tests of lepton universality in scattering. To parametrize the new physics we adopt an effective Lagrangian approach and consider the neutrino deep inelastic scattering processes tau neutrino+nucleon to tau + X and muon neutrino+nucleon to muon + X where we assume the largest new physics effects are in the tau sector. We also consider an explicit leptoquark model in our calculations. In order to make comparison with the standard model and also in order to cancel out the uncertainty of the parton …
Semi-Leptonic Decay Of Lambda-B In The Standard Model And With New Physics, Wanwei Wu
Semi-Leptonic Decay Of Lambda-B In The Standard Model And With New Physics, Wanwei Wu
Electronic Theses and Dissertations
Heavy quark decays provide a very advantageous investigation to test the Standard Model (SM). Recently, promising experiments with b quark, as well as the analysis of the huge data sets produced at the B factories, have led to an increasing study and sensitive measurements of relative b quark decays. In this thesis, I calculate various observables in the semi-leptonic decay process Λb → Λ cτν[special character omitted]τ both in the SM and in the presence of New Physics (NP) operators with different Lorentz structures. The results are relevant for the coming measurement of this semi-leptonic decay at LHC b experiment …
Biomolecular Folding Rates As Understood From Single-Reaction-Coordinate Langevin Dynamics And Kramers’ Theory, Md Adnan Kabir
Biomolecular Folding Rates As Understood From Single-Reaction-Coordinate Langevin Dynamics And Kramers’ Theory, Md Adnan Kabir
Electronic Theses and Dissertations
Langevin dynamics was used to model the folding and unfolding of simple, hairpin-like biomolecules whose ends are attached to laser-trapped beads, as occurs in optical tweezers experiments. The Langevin process was evolved numerically, using parameters motivated by real experimental systems. Folding trajectories were generated and analyzed to extract the folding rate as a function of the force applied to the beads. The observed rate was compared to the analytical predictions of Kramers' theory. Strong discrepancies were noted. The failure of the Kramers' theory was attributed to the slow dynamical response of the beads, which it does not account for. The …
Effect Of Accelerated Global Expansion On Bending Of Light, Mir Emad Aghili
Effect Of Accelerated Global Expansion On Bending Of Light, Mir Emad Aghili
Electronic Theses and Dissertations
No abstract provided.
Acousto-Electric Impedance Of Ferroelectric Phononic Superlattice, Ola Hassan Nusierat
Acousto-Electric Impedance Of Ferroelectric Phononic Superlattice, Ola Hassan Nusierat
Electronic Theses and Dissertations
The Acousto-Electric Impedance z of a Ferroelectric Phononic Superlattice (fps) is investigated. The analytical derivation of z and its phase reveal that both are functions of physical parameters such as the electromechanical coupling coefficient, the mechanical quality factor, the domain length and the phase velocity of the plate acoustic waves (paw). Mathematical code is produced that allows for modeling z in a two dimensional fps. It is observed that z depends on the number of domains in the fps structure. Fewer domains in the structure might minimize z or make it approach zero at certain conditions. A series of experiments …
Wind Induced Ground Motion, Vahid Naderyan
Wind Induced Ground Motion, Vahid Naderyan
Electronic Theses and Dissertations
Wind noise is a problem in seismic surveys and can mask the seismic signals at low frequency. Development of practical solutions to this problem must be based on a good understanding of the mechanism of the wind-ground coupling. This thesis investigates the driving pressure and shear stress perturbations on the ground surface associated with wind-induced ground motions. A prediction of the ground displacements spectra from the measured ground properties and predicted pressure and shear stress at the ground surface is developed. Field measurements are conducted at a site in Marks, MS, having a flat terrain and low ambient seismic noise …
Group Velocity Of Acoustic Waves In Plates Of Electronic Materials, Saminda Adikaram
Group Velocity Of Acoustic Waves In Plates Of Electronic Materials, Saminda Adikaram
Electronic Theses and Dissertations
In this study the propagation and dispersion characteristics of plate acoustic waves (PAW) in electronic materials are investigated experimentally. Plate acoustic waves are elastic waves that travel along a plate with thickness comparable to the wavelength of the waves. Lamb waves, a type of plate acoustic wave, have particle motion in the direction of propagation and normal to the plate. Unlike an infinite medium, plates support two sets of Lamb wave modes (symmetric and anti-symmetric) with unique velocities which depend on the relationship between the wavelength and the thickness of the plate. Out of this, two zero order modes (so …
The Behavior Of A Macroscopic Granular Material In Vortex Flow, Asami Nishikawa
The Behavior Of A Macroscopic Granular Material In Vortex Flow, Asami Nishikawa
Electronic Theses and Dissertations
A granular material is defined as a collection of discrete particles such as powder and grain. Granular materials display a large number of complex behaviors. In this project, the behavior of macroscopic granular materials under tornado-like vortex airflow, with varying airflow velocity, was observed and studied. The experimental system was composed of a 9.20-cm inner diameter acrylic pipe with a metal mesh bottom holding the particles, a PVC duct, and an airflow source controlled by a variable auto-transformer, and a power-meter. A fixed fan blade was attached to the duct's inner wall to create a tornado-like vortex airflow from straight …
Higgs Effects In Neutrino Physics And Heavy Quark Systems, Ahmed Rashed
Higgs Effects In Neutrino Physics And Heavy Quark Systems, Ahmed Rashed
Electronic Theses and Dissertations
This work presents a study of the effects of multi-Higgs doublets on the properties of neutrino sector and heavy quark systems. The phenomenological implications of multi-Higgs models, which contain multi-Higgs doublets, in the neutrino and quark sector are discussed in this dissertation. The two-Higgs-doublet model (2HDM), in which two Higgs doublets are introduced, is the simplest extension to the scalar sector of the standard model (SM). A new boson state was recently seen in the CMS (Compact Muon Solenoid) and ATLAS (A Toroidal LHC Apparatus) experiments at the LHC (Large Hadron Collider). We investigate the multi-Higgs models contributions in understanding …
Probing New Physics Through Third Generation Leptons, Preet Sharma
Probing New Physics Through Third Generation Leptons, Preet Sharma
Electronic Theses and Dissertations
This dissertation is a study of beyond standard model physics or new physics. The third generation charged lepton -the τ -is an excellent probe of new physics (NP) because of it being the heaviest lepton. As the heaviest lepton, it has the largest coupling ( among the leptons) to the Higgs boson in the Standard Model (SM). New physics contributions to the tau-neutrino nucleon scattering were considered. Charged Higgs and W' effects to the deep inelastic scattering ντ ( [special character omitted]τ) + N → τ− (τ+) + X in the neutrino-nucleon interactions has been studied. The neutrino detection process …