WITP Summer Student Symposium 2014
29 Aug 2014, Brodie Building Room 54, Brandon University
Abstracts
Gabriel Chernitsky
Quintuplet Dark Matter
A 511 keV line (gamma radiation) has been found in the Milky Way; it
is known that gamma rays are produced by positronium annihilation. In
M31 and large galaxy clusters a 3.55 keV (X-ray) signal has been
detected. There are many theories that try to explain the presence of
positronium in the Milky Way, and likewise with the X-rays from galaxy
clusters. Dark matter (DM) theories have been used in the past in
order to explain one signal or the other. We will work with a dark
matter model that will explain the origin of both signals. We
developed a mathematical model where DM has five states. The average
mass of each state is 10 GeV but each particle deviates by an energy
measure ranging from a few keV to an MeV. Adjusting the model allows
for certain DM particles decaying into positronium or X-rays, and the
strength of the interactions between states. The DM particle can
scatter into different states and affect the fractional abundance of
each level. It is important to determine the cross sectional areas for
these interactions, alongside the fractional abundance of the
different DM states, in order to have sufficient DM to produce the
gamma and X-ray signals. We have considered the particle interactions,
along with their parameters, that produce the necessary signal
strengths.
Gidon Bookatz
On locally uniformly differentiable functions over non-Archimedean ordered field
extensions of the real numbers
In a complete, real closed, non-Archimedean ordered field extension of
the real numbers, the usual notions of continuity and
differentiability induced by the order topology are too weak to extend
many of the results of real calculus such as the intermediate value
theorem, the inverse function theorem and the mean value theorem. In
this talk we will discuss locally uniformly differentiable functions
on such fields, and show how local versions of the aforementioned
theorems work for such functions.
L.J. Zhou
Spin Hall effect by surface roughness
The spin Hall effect and its inverse effect, caused by the spin orbit
interaction, provide the interconversion between spin current and
charge current. Since the effects make it possible to generate and
manipulate spin current electrically, how to realize the large effects
is an important issue in both physics and applications. To do so,
materials with heavy elements, which have strong spin orbit
interaction, have been examined so far. Here, we propose a new
mechanism to enhance the spin Hall effect without heavy elements, ie
surface roughness in metallic thin films. We examine Cu and Al thin
films with surface roughness and find that they give the spin Hall
effect comparable to that in bulk Au. We demonstrate that the spin
Hall effect induced by surface roughness has the side jump
contribution but not skew scattering.
Jarrad Perron
Geometric measure of entanglement for generalized classes of symmetric pure states
The geometric measure of entanglement is the distance or angle between
a target entangled state and the nearest unentangled state. Often one
considers the geometric measure of entanglement for highly symmetric
entangled states, which simplifies the calculations and allows for
analytic solutions. We will discuss some methods of removing certain
symmetry restrictions in order to carry out calculations for a larger
class of states.
Ryan Bergen
Matrix Representations of Feynman Diagrams
In quantum field theory, n-point functions are obtained from an
effective action. The calculation is simplified by representing the
expansion around the classical solutions as a set of Feynman
diagrams. In order to provide more computation power for physicists to
perform these calculations, I have created a new representation of
Feynman diagrams that uses adjacency matrices. I will also describe
two programs created by myself that use this representation. The
history of Feynman diagrams and its other known representations are
also briefly discussed, as well as the concept of
2-particle-irreducibility.
Brett Meggison
Scalar Field Theory
The goal of my research is to develop methods to calculate the
probability of a scattering event taking place between subatomic
particles in situations where perturbation theory is not valid. I
describe phi-4 theory and the motivations for using this theory. I
outline the computational process used to calculate scattering
amplitudes using the 2 particle irreducible effective action, with
particular emphasis on numerical techniques such as fast fourier
transforms.
Brad Cownden
Linear Perturbations of Type IIB SUGRA in Flux Compactifications
We consider linear perturbations of the background type IIB SUGRA
solutions and the effects these have on the equations of motion for
the moduli. In particular, we allow for spacetime fluctuations of the
positions of D3-branes in the compact dimensions. We postulate an
ansatz for the 5-form flux due to the D3-branes, and a compensator
field to maintain the flatness of the compact space. The movement of
the D3-branes is then shown to affect the warp factor at linear
order. We then use the equations of motion for the D3-branes, the
universal volume modulus, and the universal axion to construct a
second-order effective action.
Paul Mikula
TBA