3,850 research outputs found
A proof of the Gutzwiller Semiclassical Trace Formula using Coherent States Decomposition
The Gutzwiller semiclassical trace formula links the eigenvalues of the
Scrodinger operator ^H with the closed orbits of the corresponding classical
mechanical system, associated with the Hamiltonian H, when the Planck constant
is small ("semiclassical regime"). Gutzwiller gave a heuristic proof, using the
Feynman integral representation for the propagator of ^H. Later on
mathematicians gave rigorous proofs of this trace formula, under different
settings, using the theory of Fourier Integral Operators and Lagrangian
manifolds. Here we want to show how the use of coherent states (or gaussian
beams) allows us to give a simple and direct proof.Comment: 17 pages, LaTeX, available on http://qcd.th.u-psud.f
A Redshift Dependent Color-Luminosity Relation in Type 1a Supernovae
Type 1a supernova magnitudes are used to fit cosmological parameters under
the assumption the model will fit the observed redshift dependence. We test
this assumption with the Union 2.1 compilation of 580 sources. Several
independent tests find the existing model fails to account for a significant
correlation of supernova color and redshift. The correlation of magnitude
residuals relative to the model and has a
significance equivalent to 13 standard deviations, as evaluated by randomly
shuffling the data. Extending the existing color correction to a relation
linear in redshift improves the goodness of fit by more than 50
units, an equivalent 7- significance, while adding only one parameter.
The correlation is quite robust, cannot be attributed to
outliers, and passes several tests of consistency. We review previous hints of
redshift dependence in color parameters found in bin-by-bin fits interpreted as
parameter bias. We show that neither the bias nor the change
of our study can be explained by those effects. The previously known relation
that bluer supernovae have larger absolute luminosity tends to empirically
flatten out with increasing redshift. The best-fit cosmological dark energy
density parameter is revised from to assuming a flat universe. One possible
physical interpretation is that supernovae or their environments evolve
significantly with increasing redshift.Comment: 6 pages, 3 figures. Accepted for publication in MNRAS Letters.
Contains few corrections and extra added details to 1303.0580v
Holographic optical elements: Fabrication and testing
The basic properties and use of holographic optical elements were investigated to design and construct wide-angle, Fourier-transform holographic optical systems for use in a Bragg-effect optical memory. The performance characteristics are described along with the construction of the holographic system
Small-X Quarks at HERA Predict the Ultra High Energy Neutrino-Nucleon Cross Section
New structure function data at small Bjorken from HERA are used along
with next-to-leading order QCD evolution to predict a cross section for
charged-current interactions of ultrahigh energy neutrinos with nucleons. This
new result is over twice the size of previous estimates and has important
implications for cosmic ray experiments now underway as well as for KM3 arrays
(cubic kilometer-scale neutrino telescopes) now in the planning stages.Comment: KITCS94-9-1, 9 pages (REVTeX) plus 3 postscript figures all uuencode
Technology Update Recommendations for Construction Management Classrooms
This paper outlines the process of creating the design for technology updates to a classroom with outdated and unreliable equipment. Key features of the design include updates to the classroom’s audio and visual display systems, improved connection accessibility for presenters using personal devices, the implementation of modern recording technology to assist with virtual teaching methods, and better support for students using personal technology as their primary note-taking and working mediums. The completed elements of the project include input gathered from students, faculty, and professionals on suggestions for the design, equipment selection and justification, preliminary coordination efforts with project contractors, and recommendations for the implementation of a similar project in additional classrooms. While logistical issues prevented the timely installation of the selected technology in the originally intended classroom, the findings and recommendations outlined in this paper can serve as the foundation for the completion of the original classroom project as well as similar future projects
The Virgo Alignment Puzzle in Propagation of Radiation on Cosmological Scales
We reconsider analysis of data on the cosmic microwave background on the
largest angular scales. Temperature multipoles of any order factor naturally
into a direct product of axial quantities and cosets. Striking coincidences
exist among the axes associated with the dipole, quadrupole, and octupole CMB
moments. These axes also coincide well with two other axes independently
determined from polarizations at radio and optical frequencies propagating on
cosmological scales. The five coincident axes indicate physical correlation and
anisotropic properties of the cosmic medium not predicted by the conventional
Big Bang scenario. We consider various mechanisms, including foreground
corrections, as candidates for the observed correlations. We also consider
whether the propagation anomalies may be a signal of ``dark energy'' in the
form of a condensed background field. Perhaps {\it light propagation} will
prove to be an effective way to look for the effects of {\it dark energy}.Comment: 24 pages, 4 figures, minor changes, no change in result or
conclusions. to appear in IJMP
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