12 research outputs found
Axions and Photons In Terms of "Particles" and "Anti-Particles"
The axion photon system in an external magnetic field, when for example
considered with the geometry of the experiments exploring axion photon mixing
(which can be represented by a 1+1 effective model) displays a continuous
axion-photon duality symmetry in the limit the axion mass is neglected. The
conservation law that follows from this symmetry is obtained. The magnetic
field interaction is seen to be equivalent to first order to the interaction of
a complex charged field with an external electric potential, where this
ficticious "electric potential" is proportional to the external magnetic field.
This allows one to solve for the scattering amplitudes using already known
scalar QED results. Axion photon oscillations can be understood as violations
of a charge symmetry in the scalar QED language. Going beyond the linear
theory, the axion photon system in a self consistent magnetic field is shown,
using this formalism, to have interesting soliton solutions that represent new
non gravitational ways of trapping light. Finally, generalizing the scalar QED
formalism to 2+1 dimensions makes it clear that a photon and an axion splitt
into two components in an inhomogeneous magnetic field, an effect that reminds
us of the Stern Gerlach experiment.Comment: Talk given at the 4th Patras workshop on axions, WIMPs and WISPs,
Hamburg, Gemany, 18-21 Jun 2008. Corrected reference in version
Axions Scattering From a Quadrupole Magnetic Field
We study the 2D scattering of axions from an accelerator like quadrupole
magnet using the eikonal approximation in order to learn whether or not such a
setup could serve as a new possible method for detecting axions on terrestrial
experiments. The eikonal approximation in 2D is introduced and explained. We
also apply the eikonal approximation to two known cases in order to compare it
with previous results, obtained using Born's approximation, and discuss its
correctness
Stabilization of Neutral Thin Shells By Gravitational Effects From Electric Fields
We study the properties of a system consisting of an uncharged spherically
symmetric two dimensional extended object which encloses a stationary point
charge placed in the shell's center. We show that there can be a static and
stable configuration for the neutral shell, using only the gravitational field
of the charged source as a stabilizing mechanism. In particular, two types of
shells are studied: a dust shell and a string gas shell. The dynamical
possibilities are also analyzed, including the possibility of child universe
creation.Comment: 5 pages, 1 figur
Probing Convolutional Neural Networks for Event Reconstruction in {\gamma}-Ray Astronomy with Cherenkov Telescopes
A dramatic progress in the field of computer vision has been made in recent
years by applying deep learning techniques. State-of-the-art performance in
image recognition is thereby reached with Convolutional Neural Networks (CNNs).
CNNs are a powerful class of artificial neural networks, characterized by
requiring fewer connections and free parameters than traditional neural
networks and exploiting spatial symmetries in the input data. Moreover, CNNs
have the ability to automatically extract general characteristic features from
data sets and create abstract data representations which can perform very
robust predictions. This suggests that experiments using Cherenkov telescopes
could harness these powerful machine learning algorithms to improve the
analysis of particle-induced air-showers, where the properties of primary
shower particles are reconstructed from shower images recorded by the
telescopes. In this work, we present initial results of a CNN-based analysis
for background rejection and shower reconstruction, utilizing simulation data
from the H.E.S.S. experiment. We concentrate on supervised training methods and
outline the influence of image sampling on the performance of the CNN-model
predictions.Comment: 8 pages, 4 figures, Proceedings of the 35th International Cosmic Ray
Conference (ICRC 2017), Busan, Kore
Gravitational Trapping Near Domain Walls and Stable Solitons
In this work, the behavior of test particles near a domain wall of a stable
false vacuum bubble is studied. It is shown that matter is naturally trapped in
the vicinity of a static domain wall, and also, that there is a discontinuity
in the test particle's velocity when crossing the domain wall. The latter is
unexpected as it stands in contrast to Newtonian theory, where infinite forces
are not allowed. The weak field limit is defined in order to show that there is
no conflict with the non-relativistic behavior of gravitational fields and
particle motions under these conditions.Comment: 8 pages, 1 figure, problem is reanalyzed using a continuous
coordinate syste
Photon Production From The Scattering of Axions Out of a Solenoidal Magnetic Field
We calculate the total cross section for the production of photons from the
scattering of axions by a strong inhomogeneous magnetic field in the form of a
2D delta-function, a cylindrical step function and a 2D Gaussian distribution,
which can be approximately produced by a solenoidal current. The theoretical
result is used to estimate the axion-photon conversion probability which could
be expected in a reasonable experimental situation. The calculated conversion
probabilities for QCD inspired axions are bigger by a factor of 2.67 (for the
cylindrical step function case) than those derived by applying the celebrated
1D calculation of the (inverse) coherent Primakoff effect. We also consider
scattering at a resonance , which corresponds to the
scattering from a delta-function and gives the most enhanced results. Finally,
we analyze the results of this work in the astrophysical extension to suggest a
way in which they may be directed to a solution to some basic solar physics
problems and, in particular, the coronal heating problem.Comment: 19 pages, 1 figure, added analysis of our results in the
astrophysical extensio
Axions and Photons In Terms of Particles and Anti-Particles
The axion photon system in an external magnetic field, when for example considered with the geometry of the experiments exploring axion photon mixing (which can be represented by a 1+1 effective model) displays a continuous axion-photon duality symmetry in the limit the axion mass is neglected. The conservation law that follows from this symmetry is obtained. The magnetic field interaction is seen to be equivalent to first order to the interaction of a complex charged field with an external electric potential, where this ficticious electric potential is proportional to the external magnetic field. This allows one to solve for the scattering amplitudes using already known scalar QED results. Axion photon oscillations can be understood as violations of a charge symmetry in the scalar QED language. Going beyond the linear theory, the axion photon system in a self consistent magnetic field is shown, using this formalism, to have interesting soliton solutions that represent new non gravitational ways of trapping light. Finally, generalizing the scalar QED formalism to 2+1 dimensions makes it clear that a photon and an axion splitt into two components in an inhomogeneous magnetic field, an effect that reminds us of the Stern Gerlach experiment