1,839 research outputs found
Classical Supersymmetric Mechanics
We analyse a supersymmetric mechanical model derived from (1+1)-dimensional
field theory with Yukawa interaction, assuming that all physical variables take
their values in a Grassmann algebra B. Utilizing the symmetries of the model we
demonstrate how for a certain class of potentials the equations of motion can
be solved completely for any B. In a second approach we suppose that the
Grassmann algebra is finitely generated, decompose the dynamical variables into
real components and devise a layer-by-layer strategy to solve the equations of
motion for arbitrary potential. We examine the possible types of motion for
both bosonic and fermionic quantities and show how symmetries relate the former
to the latter in a geometrical way. In particular, we investigate oscillatory
motion, applying results of Floquet theory, in order to elucidate the role that
energy variations of the lower order quantities play in determining the
quantities of higher order in B.Comment: 29 pages, 2 figures, submitted to Annals of Physic
The dynamics of vortices on S^2 near the Bradlow limit
The explicit solutions of the Bogomolny equations for N vortices on a sphere
of radius R^2 > N are not known. In particular, this has prevented the use of
the geodesic approximation to describe the low energy vortex dynamics. In this
paper we introduce an approximate general solution of the equations, valid for
R^2 close to N, which has many properties of the true solutions, including the
same moduli space CP^N. Within the framework of the geodesic approximation, the
metric on the moduli space is then computed to be proportional to the Fubini-
Study metric, which leads to a complete description of the particle dynamics.Comment: 17 pages, 9 figure
Remarks on gauge vortex scattering
In the abelian Higgs model, among other situations, it has recently been
realized that the head-on scattering of solitons distributed symmetrically
around the point of scattering is by an angle , independant of various
details of the scattering. In this note, it is first observed that this result
is in fact not entirely surprising: the above is one of only two possible
outcomes. Then, a generalization of an argument given by Ruback for the case of
two gauge theory vortices in the Bogomol'nyi limit is used to show that in the
geodesic approximation the above result follows from purely geometric
considerations.Comment: 6 pages, revtex, missing authors added to one referenc
Calogero-Moser Models V: Supersymmetry and Quantum Lax Pair
It is shown that the Calogero-Moser models based on all root systems of the
finite reflection groups (both the crystallographic and non-crystallographic
cases) with the rational (with/without a harmonic confining potential),
trigonometric and hyperbolic potentials can be simply supersymmetrised in terms
of superpotentials. There is a universal formula for the supersymmetric ground
state wavefunction. Since the bosonic part of each supersymmetric model is the
usual quantum Calogero-Moser model, this gives a universal formula for its
ground state wavefunction and energy, which is determined purely algebraically.
Quantum Lax pair operators and conserved quantities for all the above
Calogero-Moser models are established.Comment: LaTeX2e, 31 pages, no figure
Reparametrising the Skyrme Model using the Lithium-6 Nucleus
The minimal energy B=6 solution of the Skyrme model is a static soliton with
symmetry. The symmetries of the solution imply that the quantum
numbers of the ground state are the same as those of the Lithium-6 nucleus.
This identification is considered further by obtaining expressions for the mean
charge radius and quadrupole moment, dependent only on the Skyrme model
parameters (a dimensionless constant) and (the pion decay
constant). The optimal values of these parameters have often been deliberated
upon, and we propose, for , changing them from those which are most
commonly accepted. We obtain specific values for these parameters for B=6, by
matching with properties of the Lithium-6 nucleus. We find further support for
the new values by reconsidering the -particle and deuteron as quantized
B=4 and B=2 Skyrmions.Comment: 18 page
New results on twinlike models
In this work we study the presence of kinks in models described by a single
real scalar field in bidimensional spacetime. We work within the first-order
framework, and we show how to write first-order differential equations that
solve the equations of motion. The first-order equations strongly simplify the
study of linear stability, which is implemented on general grounds. They also
lead to a direct investigation of twinlike theories, which is used to introduce
a family of models that support the same defect structure, with the very same
energy density and linear stability.Comment: 6 pages, 1 figur
Social/health maintenance organization and fee-for-service health outcomes over time.
Evaluating the performance of long-term care (LTC) demonstrations requires longitudinal assessment of multiple outcomes where selective mortality and disenrollment, if not accounted for, can give the appearance of reduced (or enhanced) efficacy. We assessed outcomes in social/health maintenance organizations (S/HMOs) and Medicare fee-for-service (FFS) care using a multivariate model to estimate active life expectancy (ALE). S/HMO enrollees and samples of FFS clients in four sites were analyzed and outcome differences assessed for a 3-year period. Results provide insights into S/HMO performance under different conditions and, more generally, into evaluating LTC demonstrations without randomized client and control groups
Performance of Electropun Polyacrylonitrile Nanofibrous Phases, Shown for the Separation of Water-Soluble Food Dyes via UTLC-Vis-ESI-MS
Research in the miniaturization of planar chromatography led to various approaches in manufacturing ultrathin-layer chromatography (UTLC) layers of reduced thickness (<50 ”m) along with smaller instrumentation, as targeted in Office Chromatography. This novel concept merges 3D print & media technologies with miniaturized planar chromatography to realize an all-in-one instrument, in which all steps of UTLC are automated and integrated in the same tiny device. In this context, the development of electrospun polyacrylonitrile (PAN) nanofiber phases was investigated as well as its performance. A nanofibrous stationary phase with fiber diameters of 150Â225 nm and a thickness of ca. 25 ”m was manufactured. Mixtures of water-soluble food dyes were printed on it using a modified office printer, and successfully separated to illustrate the capabilities of such UTLC media. The separation took 8 min for 30 mm and was faster (up to a factor of 2) than on particulate layers. The mean hRF values ranging from 25 to 90 for the five food dyes were well spread over the migration distance, with an overall reproducibility of 7% (mean %RSD over 5 different plates for 5 dyes). The individual mean plate numbers over 5 plates ranged between 8286 and 22,885 (mean of 11,722 over all 5 dyes). The single mean resolutions RS were between 1.7 and 6.5 (for the 5 food dyes over 5 plates), with highly satisfying reproducibilities (0.3 as mean deviation of RS). Using videodensitometry, different amounts separated in parallel led to reliable linear calibrations for each dye (sdv of 3.1Â9.1% for peak heights and 2.4Â9.3% for peak areas). Coupling to mass spectrometry via an elution head-based interface was successfully demonstrated for such ultrathin layers, showing several advantages such as a reduced cleaning process and a minimum zone distance. All these results underline the potential of electrospun nanofibrous phases to succeed as affordable stationary phase for quantitative UTLC
Angularly localized Skyrmions
Quantized Skyrmions with baryon numbers and 4 are considered and
angularly localized wavefunctions for them are found. By combining a few low
angular momentum states, one can construct a quantum state whose spatial
density is close to that of the classical Skyrmion, and has the same
symmetries. For the B=1 case we find the best localized wavefunction among
linear combinations of and angular momentum states. For B=2, we
find that the ground state has toroidal symmetry and a somewhat reduced
localization compared to the classical solution. For B=4, where the classical
Skyrmion has cubic symmetry, we construct cubically symmetric quantum states by
combining the ground state with the lowest rotationally excited
state. We use the rational map approximation to compare the classical and
quantum baryon densities in the B=2 and B=4 cases.Comment: 22 page
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