58,131 research outputs found
A Lattice Gauge Model of Singular Marsden-Weinstein Reduction. Part I. Kinematics
The simplest nontrivial toy model of a classical SU(3) lattice gauge theory
is studied in the Hamiltonian approach. By means of singular symplectic
reduction, the reduced phase space is constructed. Two equivalent descriptions
of this space in terms of a symplectic covering as well as in terms of
invariants are derived.Comment: 27 pages, 6 figure
Observation of the Quantum Zeno and Anti-Zeno effects in an unstable system
We report the first observation of the Quantum Zeno and Anti-Zeno effects in
an unstable system. Cold sodium atoms are trapped in a far-detuned standing
wave of light that is accelerated for a controlled duration. For a large
acceleration the atoms can escape the trapping potential via tunneling.
Initially the number of trapped atoms shows strong non-exponential decay
features, evolving into the characteristic exponential decay behavior. We
repeatedly measure the number of atoms remaining trapped during the initial
period of non-exponential decay. Depending on the frequency of measurements we
observe a decay that is suppressed or enhanced as compared to the unperturbed
system.Comment: 4 pages, 5 figures, submitted to PR
Comments concerning the paper "Measurement of negatively charged pion spectra in inelastic p+p interactions at 20, 31, 40, 80 and 158 GeV/c" by the NA61 collaboration
New data from the NA61 collaboration on the production of negative pions in
p+p interactions at beam momenta between 20 and 158 GeV/c are critically
compared to available results in the same energy range. It is concluded that
the NA61 data show some discrepancies with the previous results. This concerns
in particular the total yields, the integrated rapidity distributions and
the double differential cross sections.Comment: 16 pages, 13 figure
Magnetic Bound States in Dimerized Quantum Spin Systems
Magnetic bound states are a general phenomenon in low dimensional
antiferromagnets with gapped singlet states. Using Raman scattering on three
compounds as dedicated examples we show how exchange topology, dimensionality,
defects and thermal fluctuations influence the properties and the spectral
weight of these states.Comment: 3 pages, 1 figure, proceedings of the SCES'98, Paris, to be published
in Physica
An Introduction to Conformal Ricci Flow
We introduce a variation of the classical Ricci flow equation that modifies
the unit volume constraint of that equation to a scalar curvature constraint.
The resulting equations are named the Conformal Ricci Flow Equations because of
the role that conformal geometry plays in constraining the scalar curvature.
These equations are analogous to the incompressible Navier-Stokes equations of
fluid mechanics inasmuch as a conformal pressure arises as a Lagrange
multiplier to conformally deform the metric flow so as to maintain the scalar
curvature constraint. The equilibrium points are Einstein metrics with a
negative Einstein constant and the conformal pressue is shown to be zero at an
equilibrium point and strictly positive otherwise. The geometry of the
conformal Ricci flow is discussed as well as the remarkable analytic fact that
the constraint force does not lose derivatives and thus analytically the
conformal Ricci equation is a bounded perturbation of the classical
unnormalized Ricci equation. That the constraint force does not lose
derivatives is exactly analogous to the fact that the real physical pressure
force that occurs in the Navier-Stokes equations is a bounded function of the
velocity. Using a nonlinear Trotter product formula, existence and uniqueness
of solutions to the conformal Ricci flow equations is proven. Lastly, we
discuss potential applications to Perelman's proposed implementation of
Hamilton's program to prove Thurston's 3-manifold geometrization conjectures.Comment: 52 pages, 1 figur
The Development of an Emotional Response to Literature Measure: The Affective Response to Literature Survey
Based on theories of emotional intelligence, adult education, psychology of reading, and emotions and literature, this study was designed to develop and validate the Affective Response to Literature Survey (ARLS), a psychological instrument used to measure an emotional response to literature. Initially, 27 items were generated by a review of research relevant to emotional intelligence and emotional effects of literature. A panel of 10 experts rated 27 proposed items. After applying the content validity ratio to the expert’s ratings, 18 items were retained. The instrument was then administered to 165 individuals to assess psychometric properties. The ARLS demonstrated high internal consistency (Cronbach’s alpha=.90) and test-retest reliability (r=.90, p < .001). Factor analysis extracted four factors: (a) Reflective Synthesis, (b) Acting with Volition, (c) Processing, and (d) Empathetic Responding. The four factors have important implications for conducting research sensitive to literature, emotional intelligence, and transformational learning.Cette étude puise dans les théories portant sur le quotient émotionnel, l’éducation aux adultes, la psychologie de la lecture et les émotions et la littérature. Elle a été conçue pour le développement et la validation d’un instrument psychologique servant à mesurer la réaction affective à la littérature (Affective Response to Literature Survey, ARLS).Une analyse de la recherche relative au quotient émotionnel et à la réaction affective à la littérature a produit 27 items qu’un groupe de spécialistes a évalués. Après avoir appliqué le rapport de validité de contenu aux évaluations par les spécialistes, l’on a retenu 18 items. Par la suite, le sondage a été distribué à 165 personnes pour l’évaluation de propriétés psychométriques. Le sondage ARLS a fait preuve d’un niveau de cohérence interne (alpha de Cronbach = 0,90) et d’une fiabilité test-retest (r=0,90, p < 0,001) élevé. Quatre facteurs découlent de l’analyse: (a) synthèse réfléchie, (b) agir avec volonté, (c) traitement et (d) réaction empathique. Ces quatre facteurs jouent un rôle important dans la recherche portant sur la littérature, le quotient émotionnel et l’apprentissage transformationnel
Weak Lensing Determination of the Mass in Galaxy Halos
We detect the weak gravitational lensing distortion of 450,000 background
galaxies (20<R<23) by 790 foreground galaxies (R<18) selected from the Las
Campanas Redshift Survey (LCRS). This is the first detection of weak lensing by
field galaxies of known redshift, and as such permits us to reconstruct the
shear profile of the typical field galaxy halo in absolute physical units
(modulo H_0), and to investigate the dependence of halo mass upon galaxy
luminosity. This is also the first galaxy-galaxy lensing study for which the
calibration errors are negligible. Within a projected radius of 200 \hkpc, the
shear profile is consistent with an isothermal profile with circular velocity
164+-20 km/s for an L* galaxy, consistent with typical disk rotation at this
luminosity. This halo mass normalization, combined with the halo profile
derived by Fischer et al (2000) from lensing analysis SDSS data, places a lower
limit of (2.7+-0.6) x 10^{12}h^{-1} solar masses on the mass of an L* galaxy
halo, in good agreement with satellite galaxy studies. Given the known
luminosity function of LCRS galaxies, and the assumption that for galaxies, we determine that the mass within 260\hkpc of normal
galaxies contributes to the density of the Universe (for
) or for . These lensing data suggest
that (95% CL), only marginally in agreement with the usual
Faber-Jackson or Tully-Fisher scaling. This is the most
complete direct inventory of the matter content of the Universe to date.Comment: 18 pages, incl. 3 figures. Submitted to ApJ 6/7/00, still no response
from the referee after four months
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