4,197 research outputs found
Axially Symmetric Solutions for SU(2) Yang-Mills Theory
By casting the Yang-Mills-Higgs equations of an SU(2) theory in the form of
the Ernst equations of general relativity, it is shown how the known exact
solutions of general relativity can be used to give similiar solutions for
Yang-Mills theory. Thus all the known exact solutions of general relativity
with axial symmetry (e.g. the Kerr metric, the Tomimatsu-Sato metric) have
Yang-Mills equivalents. In this paper we only examine in detail the Kerr-like
solution. It will be seen that this solution has surfaces where the gauge and
scalar fields become infinite, which correspond to the infinite redshift
surfaces of the normal Kerr solution. It is speculated that this feature may be
connected with the confinement mechanism since any particle which carries an
SU(2) color charge would tend to become trapped once it passes these surfaces.
Unlike the Kerr solution, our solution apparently does not have any intrinsic
angular momentum, but rather appears to give the non-Abelian field
configuration associated with concentric shells of color charge.Comment: 15 pages LaTe
Subtleties in the quasi-classical calculation of Hawking radiation
he quasi-classical method of deriving Hawking radiation is investigated. In
order to recover the original Hawking temperature one must take into account a
previously ignored contribution coming from the temporal part of the action.
This contribution plus a contribution coming from the spatial part of the
action gives the correct temperature.Comment: 6 pages revtex. Honorable Mention in 2008 GRF essay contest, typos
fixed, sign errors corrected. To be published in Special Issue of IJMP
The general relativistic infinite plane
Uniform fields are one of the simplest and most pedagogically useful examples
in introductory courses on electrostatics or Newtonian gravity. In general
relativity there have been several proposals as to what constitutes a uniform
field. In this article we examine two metrics that can be considered the
general relativistic version of the infinite plane with finite mass per unit
area. The first metric is the 4D version of the 5D "brane" world models which
are the starting point for many current research papers. The second case is the
cosmological domain wall metric. We examine to what extent these different
metrics match or deviate from our Newtonian intuition about the gravitational
field of an infinite plane. These solutions provide the beginning student in
general relativity both computational practice and conceptual insight into
Einstein's field equations. In addition they do this by introducing the student
to material that is at the forefront of current research.Comment: Accepted for publication in the American Journal of Physic
Exact Schwarzschild-Like Solution for Yang-Mills Theories
Drawing on the parallel between general relativity and Yang-Mills theory we
obtain an exact Schwarzschild-like solution for SU(2) gauge fields coupled to a
massless scalar field. Pushing the analogy further we speculate that this
classical solution to the Yang-Mills equations shows confinement in the same
way that particles become confined once they pass the event horizon of the
Schwarzschild solution. Two special cases of the solution are considered.Comment: 11 pages LaTe
On the physical meaning of the Unruh effect
We present simple arguments that detectors moving with constant acceleration
(even acceleration for a finite time) should detect particles. The effect is
seen to be universal. Moreover, detectors undergoing linear acceleration and
uniform, circular motion both detect particles for the same physical reason. We
show that if one uses a circularly orbiting electron in a constant external
magnetic field as the Unruh--DeWitt detector, then the Unruh effect physically
coincides with the experimentally verified Sokolov--Ternov effect.Comment: 7 pages, 0 figures references added, small changes in text. To be
published JETP Lett
Small animal disease surveillance: respiratory disease 2017
This report focuses on surveillance for respiratory disease in companion animals. It begins with an analysis of data from 392 veterinary practices contributing to the Small Animal Veterinary Surveillance Network (SAVSNET) between January and December 2017.
The following section describes canine respiratory coronavirus infections in dogs, presenting results from laboratory-confirmed cases across the country between January 2010 and December 2017. This is followed by an update on the temporal trends of three important syndromes in companion animals, namely gastroenteritis, pruritus and respiratory disease, from 2014 to 2017.
A fourth section presents a brief update on Streptococcus equi subspecies zooepidemicus in companion animals. The final section summarises some recent developments pertinent to companion animal health, namely eyeworm (Thelazzia callipaeda) infestations in dogs imported to the UK and canine influenza virus in the USA and Canada
Opening of DNA double strands by helicases. Active versus passive opening
Helicase opening of double-stranded nucleic acids may be "active" (the
helicase directly destabilizes the dsNA to promote opening) or "passive" (the
helicase binds ssNA available due to a thermal fluctuation which opens part of
the dsNA). We describe helicase opening of dsNA, based on helicases which bind
single NA strands and move towards the double-stranded region, using a discrete
``hopping'' model. The interaction between the helicase and the junction where
the double strand opens is characterized by an interaction potential. The form
of the potential determines whether the opening is active or passive. We
calculate the rate of passive opening for the helicase PcrA, and show that the
rate increases when the opening is active. Finally, we examine how to choose
the interaction potential to optimize the rate of strand separation. One
important result is our finding that active opening can increase the unwinding
rate by 7 fold compared to passive opening.Comment: 13 pages, 3 figure
Uncovering predictability in the evolution of the WTI oil futures curve
Accurately forecasting the price of oil, the world's most actively traded
commodity, is of great importance to both academics and practitioners. We
contribute by proposing a functional time series based method to model and
forecast oil futures. Our approach boasts a number of theoretical and practical
advantages including effectively exploiting underlying process dynamics missed
by classical discrete approaches. We evaluate the finite-sample performance
against established benchmarks using a model confidence set test. A realistic
out-of-sample exercise provides strong support for the adoption of our approach
with it residing in the superior set of models in all considered instances.Comment: 28 pages, 4 figures, to appear in European Financial Managemen
Recent Advances in Unconventional Density Waves
Unconventional density wave (UDW) has been speculated as a possible
electronic ground state in excitonic insulator in 1968. Recent surge of
interest in UDW is partly due to the proposal that the pseudogap phase in high
T_c cuprate superconductors is d-wave density wave (d-DW).
Here we review our recent works on UDW within the framework of mean field
theory. In particular we have shown that many properties of the low temperature
phase (LTP) in alpha-(BEDT-TTF)_2MHg(SCN)_4 with M=K, Rb and Tl are well
characterized in terms of unconventional charge density wave (UCDW). In this
identification the Landau quantization of the quasiparticle motion in a
magnetic field (the Nersesyan effect) plays the crucial role. Indeed the
angular dependent magnetoresistance and the negative giant Nernst effect are
two hallmarks of UDW.Comment: 18 pages, 12 figure
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