Physical Sciences and Mathematics Commons^™

Two-Loop Soft Anomalous Dimensions For Single Top Quark Associated Production With A W- Or H-, Nikolaos Kidonakis

Faculty Articles

I present results for the two-loop soft anomalous dimensions for associated production of a single top quark with a W boson or a charged Higgs boson. The calculation uses expressions for the massive cusp anomalous dimension, which are presented in different forms, and it allows soft-gluon resummation at next-to-next-to-leading-logarithm (NNLL) accuracy. From the NNLL resummed cross section I derive approximate NNLO cross sections for bg→tW- and bg→tH- at LHC energies of 7, 10, and 14 TeV.

Space-Time Properties Of A Boson-Dressed Fermion For The Yukawa Model, R E. Wagner, M R. Ware, Q Su, Rainer Grobe

Faculty publications – Physics

We analyze the interaction of fermions and bosons through a one-dimensional Yukawa model. We numerically compute the energy eigenstates that represent a physical fermion, which is a superposition of bare fermionic and bosonic eigenstates of the uncoupled Hamiltonian. It turns out that even fast bare fermions require only low-momentum dressing bosons, which attach themselves to the fast fermion through quantum correlations. We compare the space-time evolution of a physical fermion with that of its bare counterpart and show the importance of using dressed observables. The time evolution of the center of mass as well as the wave packet's spatial width …

Faddeev-Type Equations For Three-Body Symmetry Violating Scattering Amplitudes, Vladimir Gudkov, Young-Ho Song

Faculty Publications

The equations which relate three-body and two-body symmetry violating scattering amplitudes are derivedin the first order of symmetry violating interactions. They can be used to obtain three-body symmetry violatingscattering amplitudes from two-body symmetry violating scattering amplitudes calculated in low energy effectivefield theory.

Time-Resolved Compton Scattering For A Model Fermion-Boson System, R E. Wagner, Rainer Grobe, Q Su

Faculty publications – Physics

We study the scattering of a boson with a fermion with full spatial and temporal resolution based on the one-dimensional Yukawa Hamiltonian. In quantum field theory this interaction is described by the annihilation and creation of bosons with intermediate virtual particle states. We show that this process can be modeled in the center-of-mass frame by a scattering potential, permitting us to interpret the absorption and re-emission processes in quantum mechanical terms of a characteristic force. This Compton force between the fermion and boson is repulsive for large distances and attractive for shorter spacings. We also examine the periodic dynamics of …

Determining Pulsation Period For An Rr Lyrae Star, Leah M. Fabrizio

Physics

No abstract provided.

Survey Of Meteorite Samples For 92nb, 98tc, And 60fe Using Gamma Ray Spectroscopy, Robert Maxwell

Physics

The focus of this senior project was the use of gamma ray spectroscopy to survey meteorite samples for 92Nb, 98Tc, and 60Fe. The presence of measurable amounts of 26Al (half-life 717,000 years) in meteorites leads astrophysists to believe that 92Nb, 98Tc, and 60Fe should also be present in detectable amounts, though they have not yet been conclusively found. Since the isotopes that were looked for in this senior project are not long lived in comparison to the age of the solar system, their presumed presence indicates that they are continuously being made in outer space and deposited on space objects.

Design Of Electronics For A High-Energy Photon Tagger For The Gluex Experiment, Mitchell "Woody" Underwood

Honors Scholar Theses

In quantum chromodynamics (QCD), quarks and antiquarks are held together inside hadrons by the nuclear strong force, which is mediated by exchange particles known as gluons. The simplest type of hadron, the meson, consists of a single quark and a single antiquark bound by a gluonic field. The flux-tube model of QCD says that this gluonic field forms a tube of color-electric field lines between the quark and the antiquark which can under the right conditions be made to vibrate. Such mesons with excited glue are called hybrid mesons.

GlueX is a high-energy nuclear physics experiment which will study hybrid …

Exponential Enhancement Of Field-Induced Pair Creation From The Bosonic Vacuum, R E. Wagner, M R. Ware, Q Su, Rainer Grobe

Faculty publications – Physics

Using numerical solutions to quantum field theory, the creation of boson-antiboson pairs from the vacuum under a very strong localized external electric field is explored. The simulations reveal that the initial linear increase of the number of particles turns into an exponential growth. This self-amplification can be understood as the result of the interaction of the previously generated particles with the creation process. While the number of particles keeps increasing, the spatial shape of the (normalized) charge density of the created particles reaches a universal form that can be related to the bound states of the supercritical potential well. We …

Neutrosophic Physics: More Problems, More Solutions, Florentin Smarandache

Branch Mathematics and Statistics Faculty and Staff Publications

When considering the laws of theoretical physics, one of the physicists says that these laws – the actual expressions of the laws of mathematics and logics being applied to physical phenomena – should be limited according to the physical meaning we attribute to the phenomena. In other word, there is an opinion that a theoretical physicist should put some limitations onto mathematics, in order to “reduce” it to the observed reality. No doubt, we can do it. However, if following this way, we would arrive at only mathematical models of already known physical phenomena. Of course, this might be useful …

Bosonic Analog Of The Klein Paradox, R E. Wagner, M R. Ware, Q Su, Rainer Grobe

Faculty publications – Physics

The standard Klein paradox describes how an incoming electron scatters off a supercritical electrostatic barrier that is so strong that it can generate electron- positron pairs. This fermionic system has been widely discussed in textbooks to illustrate some of the discrepancies between quantum mechanical and quantum field theoretical descriptions for the pair creation process. We compare the fermionic dynamics with that of the corresponding bosonic system. We point out that the direct counterpart of the Pauli exclusion principle (the central mechanism to resolve the fermionic Klein paradox) is stimulated emission, which leads to the resolution of the analogous bosonic paradox.

Starships & The Physics Of Interstellar Travel, Shane L. Larson

Public Talks

No abstract provided.

Computer-Guided Solutions To Physics Problems Using Prolog, Thomas J. Bensky, Catherine A. Taff

Physics

By posing a continual stream of pertinent questions, a nonmathematical computer program can prod freshman physics students toward an analytical solution to one-dimensional kinematics problems.

A Phenomenographic Study Of Introductory Physics Students: Approaches To Their Learning And Perceptions Of Their Learning Environment In A Physics Problem-Based Learning Environment, Paul Irving

Doctoral

This phenomenographic study describes students’ approaches to learning and their perceptions of the learning environment in an introductory physics course which is taught using a problem-based learning approach. This research builds on previous studies which showed that these students develop a greater conceptual knowledge than their counterparts in a more traditional learning environment while others showed very little development even though they engaged fully with the pedagogy. This study aimed to examine and describe the students’ approaches to learning. The definitions of surface, strategic and deep approaches to learning are not appropriate in this context and could not be applied …

Misconceptions On Force And Gravity Among High School Students, Jane Ragasa Pablico

LSU Master's Theses

The goal of this study is to determine prevalent or dominant misconceptions on force and gravity among high school students. A survey instrument consisting of 12 qualitative questions requiring both answers and written explanations was used to gather students’ ideas and beliefs in situations involving force and gravity. Furthermore, it examined whether the proportion of students having misconceptions per question are correlated with gender and the type of school Physics background. The results show that the respondents have misconceptions that are similar to the misconceptions found in previous research. The number of misconceptions and the proportion of students having misconceptions …

On Relational Quantum Mechanics, Oscar Acosta

Open Access Theses & Dissertations

A problem facing quantum mechanics is that there are a number of views or interpretations available that purport to 'explain' quantum mechanics. In this paper I discuss and analyze the view of relational quantum mechanics by Carlo Rovelli in the context of theoretical underdetermination. I will show that even though Rovelli offers a view that consolidates some of the aspects of competing theories it still falls short of breaking out of the theoretical underdetermination. The criteria that I have used to consider a theory successful in this context is one that increases the predictive output of quantum theory. Lacking an …

A Model For Predicting Extragalactic Jet Lifetimes, Daniel S. Spicer, Robert Bingham, Stephen O'Sullivan

Articles

Abstract. In this letter, we propose a model to explain the disintegration of ex- tragalactic jets and to predict the associated timescale. The model assumes that a jet is current and charge neutral as well as collimated at its source; however, the forward electron current gradually decays producing a magnetic field transverse to the direction of jet propagation. This growing transverse magnetic field eventually causes the jet to disintegrate.

Motion In Augmented Reality Games: An Engine For Creating Plausible Physical Interactions In Augmented Reality Games, Brian Mac Namee, David Beaney, Qingqing Dong

Articles

The next generation of Augmented Reality (AR) games will require real and virtual objects to coexist in motion in immersive game environments. This will require the illusion that real and virtual objects interact physically together in a plausible way. The Motion in Augmented Reality Games (MARG) engine described in this paper has been developed to allow these kinds of game environments. The paper describes the design and implementation of the MARG engine and presents two proof-of-concept AR games that have been developed using it. Evaluations of these games have been performed and are presented to show that the MARG engine …

Pair Creation Rates For One-Dimensional Fermionic And Bosonic Vacua, T Cheng, M R. Ware, Q Su, Rainer Grobe

Faculty publications – Physics

We compare the creation rates for particle-antiparticle pairs produced by a supercritical force field for fermionic and bosonic model systems. The rates obtained from the Dirac and Klein-Gordon equations can be computed directly from the quantum-mechanical transmission coefficients describing the scattering of an incoming particle with the supercritical potential barrier. We provide a unified framework that shows that the bosonic rates can exceed the fermionic ones, as one could expect from the Pauli-exclusion principle for the fermion system. This imbalance for small but supercritical forces is associated with the occurrence of negative bosonic transmission coefficients of arbitrary size for the …

Comparing Experts And Novices In Solving Electrical Circuit Problems With The Help Of Eye-Tracking, David Rosengrant, Colin Thomson, Taha Mzoughi

Faculty Articles

In order to help introductory physics students understand and learn to solve problems with circuits, we must first understand how they differ from experts. This preliminary study focuses on problem-solving dealing with electrical circuits. We investigate difficulties novices have with circuits and compare their work with those of experts. We incorporate the use of an eye-tracker to investigate any possible differences or similarities on how experts and novices solve electrical circuit problems. Our results show similarities in gaze patterns among all subjects on the components of the circuit. We further found that experts would look back at the circuit while …

Stochastic Particle Acceleration In The Lobes Of Giant Radio Galaxies, Stephen O'Sullivan, Brian Reville, Andrew Taylor

Articles

We investigate the acceleration of particles by Alfv ́en waves via the second-order Fermi process in the lobes of giant radio galaxies. Such sites are candidates for the accelerators of ultra-high-energy cosmic rays (UHECR). We focus on the nearby Fanaroff–Riley type I radio galaxy Centaurus A. This is motivated by the coincidence of its position with the arrival direction of several of the highest energy Auger events. The conditions necessary for consistency with the acceleration time-scales predicted by quasi-linear theory are reviewed. Test particle calculations are performed in fields which guarantee electric fields with no component parallel to the local …

Effects Of High-Flux Neutron Beams On He-3 Cells Polarized In Situ With Spin-Exchange Optical Pumping, E. Babcock, S. Boag, M. Becker, W. C. Chen, T. E. Chupp, T. R. Gentile, Gordon L. Jones, A. K. Petukhov, T. Soldner, T. G. Walker

Articles

Polarized He-3 produced by spin-exchange optical pumping (SEOP) has potential as a neutron spin filter for polarization and polarization analysis in many neutron-scattering and neutron particle physics applications. The advantage of the SEOP method is its suitability for providing continuous stable polarization over the course of long experiments. However, we have discovered that exposure to high neutron flux leads to additional strong relaxation mechanisms in the optically polarized alkali-metal vapor used to polarize the He-3. At a neutron flux density of 4.7 x 10(9) cm(-2) s(-1), the alkali-metal relaxation rate increased from 100 to 1000 s(-1) leading to reduced alkali-metal …

Memristive Model Of Amoeba Learning, Yuriy V. Pershin Dr, Steven La Fontaine, Massimiliano Di Ventra

Faculty Publications

Recently, it was shown that the amoebalike cell Physarum polycephalum when exposed to a pattern of periodic environmental changes learns and adapts its behavior in anticipation of the next stimulus to come. Here we show that such behavior can be mapped into the response of a simple electronic circuit consisting of a LC contour and a memory-resistor (a memristor) to a train of voltage pulses that mimic environment changes. We also identify a possible biological origin of the memristive behavior in the cell. These biological memory features are likely to occur in other unicellular as well as mutlicellular organisms, albeit …

Effect Of Cosb3 Nanoparticles On The Thermoelectric Properties Of Filled And Unfilled Cosb3 Skutterudites, Paola Alboni

All Dissertations

This study explores the possibility of somewhat decoupling the electrical and thermal conduction, thereby being able to limit the thermal conduction while minimizing the effect on the electrical conduction. The approach is using a nanoparticle layer with a slight compositional mismatch as compared to the bulk skutterudite. A hydrothermal nanoparticle-plating technique has been employed to grow a layer of CoSb₃ nanoparticles on the surface of skutterudite bulk matrix grains. Skutterudites of various forms were fabricated and studied in order to assess the effect of this nano-plated layer as a viable method in the improvement of thermoelectric properties of CoSb …

Creation Of Multiple Electron-Positron Pairs In Arbitrary Fields, T Cheng, Q Su, Rainer Grobe

Faculty publications – Physics

We examine the spontaneous breakdown of the matter vacuum triggered by an external force of arbitrary strength and spatial and temporal variations. We derive a nonperturbative framework that permits the computation of the complete time evolution of various multiple electron-positron pair probabilities. These time-dependent probabilities can be computed from a generating function as well as from solutions to a set of ratelike equations with coupling constants determined by the single-particle solutions to the time-dependent Dirac equation. This approach might be of relevance to the planned experiments to observe for the first time the laser-induced breakdown process of the vacuum.

Near-Infrared Photoabsorption By C(60) Dianions In A Storage Ring, U. Kadhane, J. U. Andersen, E. Bonderup, B. Concina, P. Hvelplund, M. Kirketerp, B. Suhr, B. Liu, S. Bronsted Nielsen, S. Panja, J. Rangama, K. Stochkel, S. Tomita

Physics & Astronomy

We present a detailed study of the electronic structure and the stability of C(60) dianions in the gas phase. Monoanions were extracted from a plasma source and converted to dianions by electron transfer in a Na vapor cell. The dianions were then stored in an electrostatic ring, and their near-infrared absorption spectrum was measured by observation of laser induced electron detachment. From the time dependence of the detachment after photon absorption, we conclude that the reaction has contributions from both direct electron tunneling to the continuum and vibrationally assisted tunneling after internal conversion. This implies that the height of the …

Two-Loop Soft Anomalous Dimensions And Next-To-Next-To-Leading-Logarithm Resummation For Heavy Quark Production, Nikolaos Kidonakis

Faculty Articles

I present results for two-loop soft anomalous dimensions for heavy quark production which control soft-gluon resummation at next-to-next-to-leading-logarithm accuracy. I derive an explicit expression for the exact result and study it numerically for top quark production via e(+) e(-) -> t (t) over bar t, and I construct a surprisingly simple but very accurate approximation. I show that the two-loop soft anomalous dimensions with massive quarks display a simple proportionality relation to the one-loop result only in the limit of vanishing quark mass. I also discuss the extension of the calculation to single top and top pair production in hadron …

African-American College Student Attitudes Toward Physics And Their Effect On Achievement, Carl Timothy Drake

Dissertations

The purpose of this study was to investigate factors affecting the attitudes that African-American college students have towards introductory college physics. The population targeted for this study consisted of African-American males and females enrolled in introductory college physics classes at an urban public historical black college or university (HBCU) located in the southeastern United States. Nine of the Fennema- Sherman Mathematics Attitude Scales, modified for physics, were used to analyze the attitudes of the 135 participants enrolled in an introductory college physics class. The nine scales used to measure the students' attitudes were Attitude Toward Success in Physics Scale (AS), …

The Equation, Spring 2009, College Of Science And Mathematics, Wright State University

College of Science and Mathematics Newsletters

This 8 page newsletter discusses various happenings within the College of Science and Mathematics. It begins with a letter from the dean, and continues on with news, events, alumni news, and other community news.

Photometric Calibrations For 21st Century Science, Stephen M. Kent, Terry D. Oswalt, Mary Elizabeth Kaiser, Et Al.

Publications

The answers to fundamental science questions in astrophysics, ranging from the history of the expansion of the universe to the sizes of nearby stars, hinge on our ability to make precise measurements of diverse astronomical objects. As our knowledge of the underlying physics of objects improves along with advances in detectors and instrumentation, the limits on our capability to extract science from measurements is set, not by our lack of understanding of the nature of these objects, but rather by the most mundane of all issues: the precision with which we can calibrate observations in physical units. We stress the …

Macrospin Model To Explain The Absence Of Preswitching Oscillations In Magnetic Tunnel Junctions: Fieldlike Spin-Transfer Torque, Samir Garzon, Yaroslaw Bazaliy, Richard A. Webb, Mark Covington, Shehzaad Kaka, Thomas M. Crawford

Faculty Publications

We show that the absence of preswitching oscillations (“incubation delay”) in magnetic tunnel junctions can be explained within the macrospin model by a sizable fieldlike component of the spin-transfer torque. It is further suggested that measurements of the voltage dependence of tunnel junction switching time in the presence of external easy axis magnetic fields can be used to determine the magnitude and voltage dependence of the fieldlike torque.