4,740 research outputs found
SLE-type growth processes and the Yang-Lee singularity
The recently introduced SLE growth processes are based on conformal maps from
an open and simply-connected subset of the upper half-plane to the half-plane
itself. We generalize this by considering a hierarchy of stochastic evolutions
mapping open and simply-connected subsets of smaller and smaller fractions of
the upper half-plane to these fractions themselves. The evolutions are all
driven by one-dimensional Brownian motion. Ordinary SLE appears at grade one in
the hierarchy. At grade two we find a direct correspondence to conformal field
theory through the explicit construction of a level-four null vector in a
highest-weight module of the Virasoro algebra. This conformal field theory has
central charge c=-22/5 and is associated to the Yang-Lee singularity. Our
construction may thus offer a novel description of this statistical model.Comment: 12 pages, LaTeX, v2: thorough revision with corrections, v3: version
to be publishe
Stationarity of SLE
A new method to study a stopped hull of SLE(kappa,rho) is presented. In this
approach, the law of the conformal map associated to the hull is invariant
under a SLE induced flow. The full trace of a chordal SLE(kappa) can be studied
using this approach. Some example calculations are presented.Comment: 14 pages with 1 figur
The mid-infrared spectrum of the transiting exoplanet HD 209458b
We report the spectroscopic detection of mid-infrared emission from the
transiting exoplanet HD 209458b. Using archive data taken with the Spitzer/IRS
instrument, we have determined the spectrum of HD 209458b between 7.46 and
15.25 microns. We have used two independent methods to determine the planet
spectrum, one differential in wavelength and one absolute, and find the results
are in good agreement. Over much of this spectral range, the planet spectrum is
consistent with featureless thermal emission. Between 7.5 and 8.5 microns, we
find evidence for an unidentified spectral feature. If this spectral modulation
is due to absorption, it implies that the dayside vertical temperature profile
of the planetary atmosphere is not entirely isothermal. Using the IRS data, we
have determined the broad-band eclipse depth to be 0.00315 +/- 0.000315,
implying significant redistribution of heat from the dayside to the nightside.
This work required development of improved methods for Spitzer/IRS data
calibration that increase the achievable absolute calibration precision and
dynamic range for observations of bright point sources.Comment: 35 pages, 12 figures, revised version accepted by the Astrophysical
Journa
Consequences of a Distant Massive Planet on the Large Semi-major Axis Trans-Neptunian Objects
We explore the distant giant planet hypothesis by integrating the large
semi-major axis, large pericenter Trans-Neptunian Objects (TNOs) in the
presence of the giant planets and an external perturber whose orbit is
consistent with the proposed distant, eccentric, and inclined giant planet, so
called planet 9. We find that TNOs with semi-major axes greater than 250 au
experience some longitude of perihelion shepherding, but that a generic outcome
of such evolutions is that the TNOs evolve to larger pericenter orbits, and
commonly get raised to retrograde inclinations. This pericenter and inclination
evolution requires a massive disk of TNOs (tens of M_\Earth) in order to
explain the detection of the known sample today. Some of the highly inclined
orbits produced by the examined perturbers will be inside of the orbital
parameter space probed by prior surveys, implying a missing signature of the
9th planet scenario. The distant giant planet scenarios explored in this work
do not reproduce the observed signal of simultaneous clustering in argument of
pericenter, longitude of the ascending node, and longitude of perihelion in the
region of the known TNOs
Emergent gauge dynamics of highly frustrated magnets
Condensed matter exhibits a wide variety of exotic emergent phenomena such as
the fractional quantum Hall effect and the low temperature cooperative behavior
of highly frustrated magnets. I consider the classical Hamiltonian dynamics of
spins of the latter phenomena using a method introduced by Dirac in the 1950s
by assuming they are constrained to their lowest energy configurations as a
simplifying measure. Focusing on the kagome antiferromagnet as an example, I
find it is a gauge system with topological dynamics and non-locally connected
edge states for certain open boundary conditions similar to doubled
Chern-Simons electrodynamics expected of a spin liquid. These dynamics
are also similar to electrons in the fractional quantum Hall effect. The
classical theory presented here is a first step towards a controlled
semi-classical description of the spin liquid phases of many pyrochlore and
kagome antiferromagnets and towards a description of the low energy classical
dynamics of the corresponding unconstrained Heisenberg models.Comment: Updated with some appendices moved to the main body of the paper and
some additional improvements. 21 pages, 5 figure
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