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Search For Nonresonant Pair Production Of Highly Energetic Higgs Bosons Decaying To Bottom Quarks, A. Tumasyan Jul 2023

Search For Nonresonant Pair Production Of Highly Energetic Higgs Bosons Decaying To Bottom Quarks, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

A search for nonresonant Higgs boson (H) pair production via gluon and vector boson (V) fusion is performed in the four-bottom-quark final state, using proton-proton collision data at 13 TeV corresponding to 138 fb−1 collected by the CMS experiment at the LHC. The analysis targets Lorentz-boosted H pairs identified using a graph neural network. It constrains the strengths relative to the standard model of the H self-coupling and the quartic VVHH couplings, κ2V, excluding κ2V = 0 for the first time, with a significance of 6.3 standard deviations when other H couplings …


Wave Optics Approach To Solar Cell Brdf Modeling With Experimental Results, Madilynn Compean, Todd V. Small, Milo W. Hyde Iv, Michael Marciniak Jul 2023

Wave Optics Approach To Solar Cell Brdf Modeling With Experimental Results, Madilynn Compean, Todd V. Small, Milo W. Hyde Iv, Michael Marciniak

Faculty Publications

Light curve analysis is often used to discern information about satellites in geosynchronous orbits. Solar panels, comprising a large part of the satellite’s body, contribute significantly to these light curves. Historically, theoretical bidirectional reflectance distribution functions (BRDFs) have failed to capture key features in the scattered light from solar panels. In recently published work, a new solar cell BRDF was developed by combining specular microfacet and “two-slit” diffraction terms to capture specular and periodic/array scattering, respectively. This BRDF was experimentally motivated and predicted many features of the solar cell scattered irradiance. However, the experiments that informed the BRDF were limited …


Self-Inductance And Magnetic Flux, Diego Castano, Teresa M. Castano Jul 2023

Self-Inductance And Magnetic Flux, Diego Castano, Teresa M. Castano

Chemistry and Physics Faculty Articles

The canonical equation for self-inductance involving magnetic flux is examined, and a more general form is presented that can be applied to continuous current distributions. We attempt to clarify and extend the use of the standard equation by recasting it in its more versatile form.


Density Dependence And Dynamics Of Dipole-Dipole Interactions Among Rydberg Atoms, Hannah Conley Jul 2023

Density Dependence And Dynamics Of Dipole-Dipole Interactions Among Rydberg Atoms, Hannah Conley

Physics and Astronomy Summer Fellows

After trapping atoms, exciting them to an initial high-energy Rydberg state, and allowing them a brief time to exchange energy with each other through dipole-dipole interactions, we observe how their energies are redistributed among various energy levels. The measurements we make in this physical experiment do not give insight into how individual atoms interact or metrics like fidelity and entanglement entropy, which impact our results. For this reason, it is useful to compare our results from the physical experiment to those of our simulation on a supercomputer, in which we can track the final and initial energy of individual atoms …


Gamma-Ray Spectroscopy Of One-Neutron Knockout From 72se, Alyssa Himmelreich Jul 2023

Gamma-Ray Spectroscopy Of One-Neutron Knockout From 72se, Alyssa Himmelreich

Physics and Astronomy Summer Fellows

We studied single-neuron excitations of the exotic nucleus 71Se with the one-neutron knockout reaction from a 72Se beam at the National Superconducting Cyclotron Laboratory. We measured gamma rays de-exciting states in 71Se using the Gretina gamma-ray tracking array and the momentum of the 71Se reaction product with the S800 Magnetic Spectrograph. We utilize a supercomputer to run multiple simulations and fit them to our gamma-ray spectrum. Using gamma-ray yields and level schemes, we can determine the number of times each excited state was populated by neutron knockout. We deduced cross sections for populating single-neutron excitations of …


Enhanced Quantum Chemistry With Machine Learning, Brock Dyer Jul 2023

Enhanced Quantum Chemistry With Machine Learning, Brock Dyer

Physics and Astronomy Summer Fellows

This file is a catalogue of the relevant quantum mechanical and computer programming topics that I learned during the summer which will be helping me to generate an artificial intelligence that will be able to perform computational chemical calculations at a much faster rate and comparable or better accuracy than current methods.


Improving The Efficiency Of Liquid-Hydrogen Simulation Via Event Storage, Jake Kosa Jul 2023

Improving The Efficiency Of Liquid-Hydrogen Simulation Via Event Storage, Jake Kosa

Physics and Astronomy Summer Fellows

We contributed to the analysis of gamma-ray spectroscopy data collected at the Facility for Rare Isotope Beams at Michigan State University by speeding up the UCGretina simulation code, used in the analysis and planning of experiments. Simulating beam-target interactions in a liquid-hydrogen target system is a time intensive task, even when parallelized. In the process of analyzing data, a large number of simulations must be run for different gamma-ray energies, target positions, and lifetimes of excited states. We are addressing the most computationally intensive component of the simulations by adding the ability to simulate a large sample of beam particles …


Two-Particle Azimuthal Correlations In Γp Interactions Using Ppb Collisions At √SNn=8.16tev, A. Tumasyan Jul 2023

Two-Particle Azimuthal Correlations In Γp Interactions Using Ppb Collisions At √SNn=8.16tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

The first measurements of the Fourier coefficients (VnΔ) of the azimuthal distributions of charged hadrons emitted from photon-proton (γp) interactions are presented. The data are extracted from 68.8nb−1of ultra-peripheral proton-lead (pPb) collisions at √sNN=8.16 TeVusing the CMS detector. The high energy lead ions produce a flux of photons that can interact with the oncoming proton. This γp system provides a set of unique initial conditions with multiplicity lower than in photon-lead collisions but comparable to recent electron-positron and electron-proton data. The VnΔ coefficients are presented in ranges of event multiplicity and transverse momentum …


A Method For Calculating Lateral Surface Area Of Bistatic Radar Beam Overlap, James I. Murray, Fredrick A. Jenet Jul 2023

A Method For Calculating Lateral Surface Area Of Bistatic Radar Beam Overlap, James I. Murray, Fredrick A. Jenet

Physics & Astronomy Faculty Publications

It has been shown that bistatic radars using radio telescopes as receivers can be used to increase the sensitivity of orbital debris measurements over traditional terrestrial monostatic radar. A method to calculate the lateral surface area of a bistatic radar is needed to evaluate the efficacy of a proposed bistatic radar configuration for orbital debris measurements. For over three decades, models of the orbital debris (OD) environment in low Earth orbit (LEO) have been developed to assess the risk posed by OD to spacecraft. While terrestrial radar measures debris 3 mm and larger and in situ measurements provide data for …


Search For Medium Effects Using Jets From Bottom Quarks In Pbpb Collisions At √SNn=5.02tev, A. Tumasyan Jul 2023

Search For Medium Effects Using Jets From Bottom Quarks In Pbpb Collisions At √SNn=5.02tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

The first study of the shapes of jets arising from bottom (b) quarks in heavy ion collisions is presented. Jet shapes are studied using charged hadron constituents as a function of their radial distance from the jet axis. Lead-lead (PbPb) collision data at a nucleon-nucleon center-of-mass energy of √sNN=5.02TeVwere recorded by the CMS detector at the LHC, with an integrated luminosity of 1.69nb−1. Compared to proton-proton collisions, aredistribution of the energy inbjets to larger distances from the jet axis is observed in PbPb collisions. This medium-induced redistribution is found to be substantially larger forbjets than for …


Enhanced Acousto-Optic Properties Of Silicon Carbide Based Layered Structure, Namrata Dewan Soni Jul 2023

Enhanced Acousto-Optic Properties Of Silicon Carbide Based Layered Structure, Namrata Dewan Soni

Al-Bahir

This study investigates the feasibility of using silicon carbide-based layered surface acoustic wave (SAW) devices in acousto-optic applications. The acousto-optic properties of the temperature-stable layered structure TeO3/SiC/128oY-X LiNbO3 are investigated through theoretical analysis. This analysis includes the evaluation of key parameters such as the overlap integral, figure of merit, and diffraction efficiency. The SAW propagation characteristics and field profiles required for these calculations are obtained using SAW software. Results show that the layered structure has high diffraction efficiency of nearly 96% and a promising value for the acousto-optic figure of merit, indicating potential use in low driving power acousto-optic devices. …


Search For New Heavy Resonances Decaying To Ww, Wz, Zz, Wh, Or Zh Boson Pairs In The All-Jets Final State In Proton-Proton Collisions At √S=13 Tev, A. Tumasyan Jul 2023

Search For New Heavy Resonances Decaying To Ww, Wz, Zz, Wh, Or Zh Boson Pairs In The All-Jets Final State In Proton-Proton Collisions At √S=13 Tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

A search for new heavy resonances decaying to WW, WZ, ZZ, WH, or ZHboson pairs in the all-jets final state is presented. The analysis is based on proton-proton collision data recorded by the CMS detector in 2016–2018 at a centre-of-mass energy of 13TeVat the CERN LHC, corresponding to an integrated luminosity of 138fb−1. The search is sensitive to resonances with masses between 1.3and 6 TeV, decaying to bosons that are highly Lorentz-boosted such that each of the bosons forms a single large-radius jet. Machine learning techniques are employed to identify such jets. No significant excess over the estimated …


Search For Narrow Resonances In The B-Tagged Dijet Mass Spectrum In Proton-Proton Collisions At √S=13 Tev, A. Tumasyan Jul 2023

Search For Narrow Resonances In The B-Tagged Dijet Mass Spectrum In Proton-Proton Collisions At √S=13 Tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

A search is performed for narrow resonances decaying to final states of two jets, with at least one jet originating from a b quark, in proton-proton collisions at √s = 13 TeV. The data set corresponds to an integrated luminosity of 138 fb−1 collected with theCMS detector at the LHC. Jets originating from energetic b hadrons are identified through a b-tagging algorithm that utilizes a deep neural network or the presence of a muon inside a jet. The invariant mass spectrum of jet pairs is well described by a smooth parametrization and no evidence for the production of …


Nonlinear Optical Studies At Surfaces And Interfaces, Mojgan Dehghani Jul 2023

Nonlinear Optical Studies At Surfaces And Interfaces, Mojgan Dehghani

LSU Doctoral Dissertations

Nonlinear optical studies have revealed that surfaces and interfaces possess unique optical properties due to the lack of inversion symmetry. These properties are significantly different from those of the bulk material. Second harmonic generation (SHG), a second-order nonlinear optical phenomenon, has emerged as a surface-specific technique to study these unique properties. The powerful selection rule allows generation of second harmonic light only in the bulk of noncentrosymmetric media and the regions with broken inversion symmetry, including surfaces and interfaces. The generated second harmonic provides significant information on the electronic and structural properties of the microscopic surface layer at the boundary …


Noise Analysis Of The Indian Pulsar Timing Array Data Release I, Aman Srivastava, Shantanu Desai, Neel Kolhe, Mayuresh Surnis, Bhal Chandra Joshi, Abhimanyu Susobhanan, Aurélien Chalumeau, Shinnosuke Hisano, Nobleson K, Raghav Girgaonkar Jul 2023

Noise Analysis Of The Indian Pulsar Timing Array Data Release I, Aman Srivastava, Shantanu Desai, Neel Kolhe, Mayuresh Surnis, Bhal Chandra Joshi, Abhimanyu Susobhanan, Aurélien Chalumeau, Shinnosuke Hisano, Nobleson K, Raghav Girgaonkar

Physics & Astronomy Faculty Publications

The Indian Pulsar Timing Array (InPTA) collaboration has recently made its first official data release (DR1) for a sample of 14 pulsars using 3.5 years of uGMRT observations. We present the results of single-pulsar noise analysis for each of these 14 pulsars using the InPTA DR1. For this purpose, we consider white noise, achromatic red noise, dispersion measure (DM) variations, and scattering variations in our analysis. We apply Bayesian model selection to obtain the preferred noise models among these for each pulsar. For PSR J1600−3053, we find no evidence of DM and scattering variations, while for PSR J1909−3744, we find …


Implementation Of An Efficient Bayesian Search For Gravitational-Wave Bursts With Memory In Pulsar Timing Array Data, Jerry Sun, Paul T. Baker, Aaron D. Johnson, Dustin R. Madison, Xavier Siemens Jul 2023

Implementation Of An Efficient Bayesian Search For Gravitational-Wave Bursts With Memory In Pulsar Timing Array Data, Jerry Sun, Paul T. Baker, Aaron D. Johnson, Dustin R. Madison, Xavier Siemens

Pacific Faculty Work

The standard Bayesian technique for searching pulsar timing data for gravitational-wave bursts with memory (BWMs) using Markov Chain Monte Carlo (MCMC) sampling is very computationally expensive to perform. In this paper, we explain the implementation of an efficient Bayesian technique for searching for BWMs. This technique makes use of the fact that the signal model for Earth-term BWMs (BWMs passing over the Earth) is fully factorizable. We estimate that this implementation reduces the computational complexity by a factor of 100. We also demonstrate that this technique gives upper limits consistent with published results using the standard Bayesian technique, and may …


Entanglement In The Hawking Effect: From Astrophysical To Optical Black Holes, Dimitrios Kranas Jul 2023

Entanglement In The Hawking Effect: From Astrophysical To Optical Black Holes, Dimitrios Kranas

LSU Doctoral Dissertations

The Hawking effect is an exciting physical prediction lying at the intersection of the two most successful theories of the past century, namely, Einstein’s theory of relativity and quantum mechanics. In this dissertation, we put special emphasis on the quantum aspects of the Hawking process encoded in the entanglement shared by the emitted fluxes of created quanta. In particular, we employ sharp tools from quantum information theory to quantify the entanglement produced by the Hawking effect throughout the black hole evaporation process. Our framework allows us to extend previous calculations of entanglement to a larger set of cases, for instance, …


Probing Heavy Majorana Neutrinos And The Weinberg Operator Through Vector Boson Fusion Processes In Proton-Proton Collisions At √S = 13 Tev, A. Tumasyan Jul 2023

Probing Heavy Majorana Neutrinos And The Weinberg Operator Through Vector Boson Fusion Processes In Proton-Proton Collisions At √S = 13 Tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

The first search exploiting the vector boson fusion process to probe heavy Majorana neutrinos and the Weinberg operator at the LHC is presented. The search is performed in the same-sign dimuon final state using a proton-proton collision dataset recorded at √s = 13 TeV, collected with the CMS detector and corresponding to a total integrated luminosity of 138 fb−1. The results are found to agree with the predictions of the standard model. For heavy Majorana neutrinos, constraints on the squared mixing element between the muon and the heavy neutrino are derived in the heavy neutrino mass range 50 …


Application Of A Diatomic Molecule Model Potential To A Series Of Homo- And Heterodiatomic Molecules, Dorien E. Carpenter, Javier E. Hasbun Jul 2023

Application Of A Diatomic Molecule Model Potential To A Series Of Homo- And Heterodiatomic Molecules, Dorien E. Carpenter, Javier E. Hasbun

Georgia Journal of Science

We apply a one-dimensional classical model of a diatomic molecule model potential with modifications to H2, HF, LiF, N2, and CO. We obtain the unknown parameters of this model by digitizing plots of the potential curves for the molecules from a published, Hartree-Fock based theoretical electron correlation calculation (Piris 2017). We then apply the method of successive approximations to the model in order to calculate the wavenumber for each molecule in the series. The wavenumber depends on a parameter which in turn depends on the initial conditions. The value of this parameter for each individual molecule …


The Next Generation Virgo Cluster Survey (Ngvs). Xxxv. First Kinematical Clues Of Overly Massive Dark Matter Halos In Several Ultradiffuse Galaxies In The Virgo Cluster, Elisa Toloba, Laura V. Sales, Sungsoon Lim, Eric W. Peng, Puragra Guhathakurta, Joel Roediger, Kaixiang Wang, J. Christopher Mihos, Patrick Côté, Patrick R. Durrell, Laura Ferrarese Jul 2023

The Next Generation Virgo Cluster Survey (Ngvs). Xxxv. First Kinematical Clues Of Overly Massive Dark Matter Halos In Several Ultradiffuse Galaxies In The Virgo Cluster, Elisa Toloba, Laura V. Sales, Sungsoon Lim, Eric W. Peng, Puragra Guhathakurta, Joel Roediger, Kaixiang Wang, J. Christopher Mihos, Patrick Côté, Patrick R. Durrell, Laura Ferrarese

Pacific Faculty Work

We present Keck/DEIMOS spectroscopy of the first complete sample of ultradiffuse galaxies (UDGs) in the Virgo cluster. We select all UDGs in Virgo that contain at least 10 globular cluster (GC) candidates and are more than 2.5σ outliers in scaling relations of size, surface brightness, and luminosity (a total of 10 UDGs). We use the radial velocity of their GC satellites to measure the velocity dispersion of each UDG. We find a mixed bag of galaxies, from one UDG that shows no signs of dark matter, to UDGs that follow the luminosity-dispersion relation of early-type galaxies, to the most extreme …


A Statistical Framework For Automating Resonance Detection: Modelling Pion Proton Collision Activity, Shahnaz Abdul Hameed Jul 2023

A Statistical Framework For Automating Resonance Detection: Modelling Pion Proton Collision Activity, Shahnaz Abdul Hameed

2023 REYES Proceedings

In this paper, we analyze π− − p elastic collision data from the Particle Data Group (PDG), by creating a general framework to study resonance activity: automating peak detection, extrapolating, parametrizing thresholds, filtering resonances and further comparing and extracting characteristics, to identify Delta (Δ) baryons. We then analyse experimental Energy vs Phase-Shift (δ) data for the collision π+ +π− → π− +π+, model the T matrix from a curve fitted polynomial representation of the K−1 matrix, simulate its Riemann sheets and analyse it to identify the characteristics of ρ0(770) meson, as well as estimate their uncertainties. …


Numerical Design And Optimization Of Near-Infrared Band- Pass Filter, Hafiza Syeeda Faiza, Ghazi Aman Nowsherwan, Basem A. Abu Izneid, Muhammad Azhar, Saira Riaz, Syed Sajjad Hussain, Saira Ikram, Mohsin Khan, Shahzad Naseem, Mohammad Kanan, Ibrahim M. Mansour Jul 2023

Numerical Design And Optimization Of Near-Infrared Band- Pass Filter, Hafiza Syeeda Faiza, Ghazi Aman Nowsherwan, Basem A. Abu Izneid, Muhammad Azhar, Saira Riaz, Syed Sajjad Hussain, Saira Ikram, Mohsin Khan, Shahzad Naseem, Mohammad Kanan, Ibrahim M. Mansour

Applied Mathematics & Information Sciences

Band-pass filters functioning in the near-infrared (IR) range are desired for laser technology, multi-photon fluorescence, and IR imaging applications. In this study, we have designed four band-pass filters in the near Infrared spectrum (900-1200 nm) by vertically stacking different high and low-index materials. The band-pass filters are modelled by Essential Macleod software with different thicknesses. The layer’s thicknesses were optimized in such a way to provide the negligible reflectance and maximum transmission on the front side. All the simulated band-pass filters exhibit high transmittance, but TiO2/Al2O3 and Ta2O5/Al2O3 outperforms other modelled structure in terms of performance due to the better …


Hypo-Osmotic Stress And Pore-Forming Toxins Adjust The Lipid Order In Sheep Red Blood Cell Membranes, Rose Whiting, Sevio Stanton, Maryna Kucheriava, Aviana R. Smith, Matt Pitts, Daniel Robertson, Jacob Kammer, Zhiyu Li, Daniel Fologea Jul 2023

Hypo-Osmotic Stress And Pore-Forming Toxins Adjust The Lipid Order In Sheep Red Blood Cell Membranes, Rose Whiting, Sevio Stanton, Maryna Kucheriava, Aviana R. Smith, Matt Pitts, Daniel Robertson, Jacob Kammer, Zhiyu Li, Daniel Fologea

Physics Faculty Publications and Presentations

Lipid ordering in cell membranes has been increasingly recognized as an important factor in establishing and regulating a large variety of biological functions. Multiple investigations into lipid organization focused on assessing ordering from temperature-induced phase transitions, which are often well outside the physiological range. However, particular stresses elicited by environmental factors, such as hypo-osmotic stress or protein insertion into membranes, with respect to changes in lipid status and ordering at constant temperature are insufficiently described. To fill these gaps in our knowledge, we exploited the well-established ability of environmentally sensitive membrane probes to detect intramembrane changes at the molecular level. …


Development And Reliability Analysis Of A Split-Administration Test Of The Math Epistemic Games Survey, Stephen Hackler, E. Elliott, M. Eichenlaub, Alison M. Sweeney Jul 2023

Development And Reliability Analysis Of A Split-Administration Test Of The Math Epistemic Games Survey, Stephen Hackler, E. Elliott, M. Eichenlaub, Alison M. Sweeney

Physics & Astronomy Faculty Works

The increasing and diversifying student enrollments in introductory physics courses make reliable, valid, and usable instruments for measuring student skills and gains ever more important. In introductory physics, in addition to teaching facts about mechanics, we also seek to teach our students the skills of “thinking like a physicist,” or expertise in and intuition for physical problem solving. How and when these expert, intuitive problem-solving skills emerge during a STEM education, or what the most effective teaching methods might be, are not certain. A facile survey to measure students’ “physics-thinking” skills in a pretest and post-test format is therefore desirable …


Studying The Topological Sector Of Quantum Gravity With Branched Covering Spaces, Christopher L. Duston Jul 2023

Studying The Topological Sector Of Quantum Gravity With Branched Covering Spaces, Christopher L. Duston

Physics Faculty Publications

Spatial topology change is generally expected to be prohibited classically, being present only at the quantum scale. However, including topology change into many of the current approaches to quantum gravity (such as Loop Quantum Gravity (LQG) and Causal Dynamical Triangulations (CDT)) has proven difficult for technical reasons. In this work we explore this sector numerically using branched covering spaces (in LQG this corresponds to the utilization of Topspin Networks). To this end, we have implemented a group-theoretic algorithm coming from knot theory to measure the topology of arbitrary spatial sections in a systematic way, and have constructed a statistical ensemble …


Modified Geometries, Clifford Algebras And Graphs: Their Impact On Discreteness, Locality And Symmetr, Roman Sverdlov Jul 2023

Modified Geometries, Clifford Algebras And Graphs: Their Impact On Discreteness, Locality And Symmetr, Roman Sverdlov

Mathematics & Statistics ETDs

In this dissertation I will explore the question whether various entities commonly used in quantum field theory can be “constructed". In particular, can spacetime be “constructed" out of building blocks, and can Berezin integral be “constructed" in terms of Riemann integrals.

As far as “constructing" spacetime out of building blocks, it has been attempted by multiple scientific communities and various models were proposed. But the common downfall is they break the principles of relativity. I will explore the ways of doing so in such a way that principles of relativity are respected. One of my approaches is to replace points …


Computational Model Of Twisted Elastic Ribbons, Madelyn Leembruggen, Jovana Andrejevic, Arshad Kudrolli, Chris H. Rycroft Jul 2023

Computational Model Of Twisted Elastic Ribbons, Madelyn Leembruggen, Jovana Andrejevic, Arshad Kudrolli, Chris H. Rycroft

Physics

We develop an irregular lattice mass-spring model to simulate and study the deformation modes of a thin elastic ribbon as a function of applied end-to-end twist and tension. Our simulations reproduce all reported experimentally observed modes, including transitions from helicoids to longitudinal wrinkles, creased helicoids and loops with self-contact, and transverse wrinkles to accordion self-folds. Our simulations also show that the twist angles at which the primary longitudinal and transverse wrinkles appear are well described by various analyses of the Föppl-von Kármán equations, but the characteristic wavelength of the longitudinal wrinkles has a more complex relationship to applied tension than …


Density-Mediated Spin Correlations Drive Edge-To-Bulk Flow Transition In Active Chiral Matter, Alexander P. Petroff, Christopher Whittington, Arshad Kudrolli Jul 2023

Density-Mediated Spin Correlations Drive Edge-To-Bulk Flow Transition In Active Chiral Matter, Alexander P. Petroff, Christopher Whittington, Arshad Kudrolli

Physics

We demonstrate that edge currents develop in active chiral matter due to boundary shielding over a wide range of densities corresponding to a gas, fluid, and crystal. The system is composed of spinning disk-shaped grains with chirally arranged tilted legs confined in a circular vibrating chamber. The edge currents are shown to increasingly drive circulating bulk flows with area fraction as percolating clusters develop due to increasing spin-coupling between neighbors mediated by frictional contacts. Edge currents are observed even in the dilute limit. While, at low area fraction, the average flux vanishes except within a distance that is of the …


Logarithmic Terms In Atom-Surface Potentials: Limited Applicability Of Rational Approximations For Intermediate Distance, Ulrich D. Jentschura, C. Moore Jul 2023

Logarithmic Terms In Atom-Surface Potentials: Limited Applicability Of Rational Approximations For Intermediate Distance, Ulrich D. Jentschura, C. Moore

Physics Faculty Research & Creative Works

It is usually assumed that interaction potentials, in general, and atom-surface potential, in particular, can be expressed in terms of an expansion involving integer powers of the distance between the two interacting objects. Here, we show that, in the short-range expansion of the interaction potential of a neutral atom and a dielectric surface, logarithms of the atom-wall distance appear. These logarithms are accompanied with logarithmic sums over virtual excitations of the atom interacting with the surface in analogy to Bethe logarithms in quantum electrodynamics. We verify the presence of the logarithmic terms in the short-range expansion using a model problem …


Algebraic Approach To Relativistic Landau Levels In The Symmetric Gauge, Ulrich D. Jentschura Jul 2023

Algebraic Approach To Relativistic Landau Levels In The Symmetric Gauge, Ulrich D. Jentschura

Physics Faculty Research & Creative Works

We use an algebraic approach to the calculation of Landau levels for a uniform magnetic field in the symmetric gauge with a vector potential A→=12(B→xr→), where B→ is assumed to be constant. The magnetron quantum number constitutes the degeneracy index. An overall complex phase of the wave function, given in terms of Laguerre polynomials, is a consequence of the algebraic structure. The relativistic generalization of the treatment leads to fully relativistic bispinor Landau levels in the symmetric gauge, in a representation which writes the relativistic states in terms of their nonrelativistic limit, and an algebraically accessible lower bispinor component. Negative-energy …