5,314 research outputs found
Measurement of Holmium Rydberg series through MOT depletion spectroscopy
We report measurements of the absolute excitation frequencies of Ho
and odd-parity Rydberg series. The states are
detected through depletion of a magneto-optical trap via a two-photon
excitation scheme. Measurements of 162 Rydberg levels in the range
yield quantum defects well described by the Rydberg-Ritz formula. We observe a
strong perturbation in the series around due to an unidentified
interloper at 48515.47(4) cm. From the series convergence, we determine
the first ionization potential cm, which is
three orders of magnitude more accurate than previous work. This work
represents the first time such spectroscopy has been done in Holmium and is an
important step towards using Ho atoms for collective encoding of a quantum
register.Comment: 6 figure
Determinantal Correlations of Brownian Paths in the Plane with Nonintersection Condition on their Loop-Erased Parts
As an image of the many-to-one map of loop-erasing operation \LE of random
walks, a self-avoiding walk (SAW) is obtained. The loop-erased random walk
(LERW) model is the statistical ensemble of SAWs such that the weight of each
SAW is given by the total weight of all random walks which are
inverse images of , \{\pi: \LE(\pi)=\zeta \}. We regard the Brownian
paths as the continuum limits of random walks and consider the statistical
ensemble of loop-erased Brownian paths (LEBPs) as the continuum limits of the
LERW model. Following the theory of Fomin on nonintersecting LERWs, we
introduce a nonintersecting system of -tuples of LEBPs in a domain in
the complex plane, where the total weight of nonintersecting LEBPs is given by
Fomin's determinant of an matrix whose entries are boundary
Poisson kernels in . We set a sequence of chambers in a planar domain and
observe the first passage points at which Brownian paths first enter each chamber, under the condition that the loop-erased
parts (\LE(\gamma_1),..., \LE(\gamma_N)) make a system of nonintersecting
LEBPs in the domain in the sense of Fomin. We prove that the correlation
functions of first passage points of the Brownian paths of the present system
are generally given by determinants specified by a continuous function called
the correlation kernel. The correlation kernel is of Eynard-Mehta type, which
has appeared in two-matrix models and time-dependent matrix models studied in
random matrix theory. Conformal covariance of correlation functions is
demonstrated.Comment: v3: REVTeX4, 27 pages, 10 figures, corrections made for publication
in Phys.Rev.
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
Stochastic evolutions in superspace and superconformal field theory
Some stochastic evolutions of conformal maps can be described by SLE and may
be linked to conformal field theory via stochastic differential equations and
singular vectors in highest-weight modules of the Virasoro algebra. Here we
discuss how this may be extended to superconformal maps of N=1 superspace with
links to superconformal field theory and singular vectors of the N=1
superconformal algebra in the Neveu-Schwarz sector.Comment: 13 pages, LaTe
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
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
Transforming fixed-length self-avoiding walks into radial SLE_8/3
We conjecture a relationship between the scaling limit of the fixed-length
ensemble of self-avoiding walks in the upper half plane and radial SLE with
kappa=8/3 in this half plane from 0 to i. The relationship is that if we take a
curve from the fixed-length scaling limit of the SAW, weight it by a suitable
power of the distance to the endpoint of the curve and then apply the conformal
map of the half plane that takes the endpoint to i, then we get the same
probability measure on curves as radial SLE. In addition to a non-rigorous
derivation of this conjecture, we support it with Monte Carlo simulations of
the SAW. Using the conjectured relationship between the SAW and radial SLE, our
simulations give estimates for both the interior and boundary scaling
exponents. The values we obtain are within a few hundredths of a percent of the
conjectured values
Improved V II log() Values, Hyperfine Structure Constants, and Abundance Determinations in the Photospheres of the Sun and Metal-poor Star HD 84937
New experimental absolute atomic transition probabilities are reported for
203 lines of V II. Branching fractions are measured from spectra recorded using
a Fourier transform spectrometer and an echelle spectrometer. The branching
fractions are normalized with radiative lifetime measurements to determine the
new transition probabilities. Generally good agreement is found between this
work and previously reported V II transition probabilities. Use of two
spectrometers, independent radiometric calibration methods, and independent
data analysis routines enables a reduction in systematic uncertainties, in
particular those due to optical depth errors. In addition, new hyperfine
structure constants are measured for selected levels by least squares fitting
line profiles in the FTS spectra. The new V II data are applied to high
resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to
determine new, more accurate V abundances. Lines covering a range of wavelength
and excitation potential are used to search for non-LTE effects. Very good
agreement is found between our new solar photospheric V abundance, log
{\epsilon}(V) = 3.95 from 15 V II lines, and the solar-system meteoritic value.
In HD 84937, we derive [V/H] = -2.08 from 68 lines, leading to a value of
[V/Fe] = 0.24.Comment: 32 pages, 7 tables (3 machine-readable), 8 figures; accepted for
publication in ApJ
Lifetimes, transition probabilities, and level energies in Fe I
We use time-resolved laser-induced fluorescence to measure the lifetime of 186 Fe levels with energies between 25 900 and 60 758 cm . Measured emission branching fractions for these levels yield transition probabilities for 1174 transitions in the range 225-2666 nm. We find another 640 Fe transition probabilities by interpolating level populations in the inductively coupled plasma spectral source. We demonstrate the reliability of the interpolation method by comparing our transition probabilities with absorption oscillator strengths measured by the Oxford group [Blackwell et al., Mon. Not. R. Astron. Soc. 201, 595-602 (1982)]. We derive precise Fe level energies to support the automated method that is used to identify transitions in our spectra
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