2,391 research outputs found
An Algebraic Model for the Multiple Meixner Polynomials of the First Kind
An interpretation of the multiple Meixner polynomials of the first kind is
provided through an infinite Lie algebra realized in terms of the creation and
annihilation operators of a set of independent oscillators. The model is used
to derive properties of these orthogonal polynomials
Quantum Algebraic Approach to Refined Topological Vertex
We establish the equivalence between the refined topological vertex of
Iqbal-Kozcaz-Vafa and a certain representation theory of the quantum algebra of
type W_{1+infty} introduced by Miki. Our construction involves trivalent
intertwining operators Phi and Phi^* associated with triples of the bosonic
Fock modules. Resembling the topological vertex, a triple of vectors in Z^2 is
attached to each intertwining operator, which satisfy the Calabi-Yau and
smoothness conditions. It is shown that certain matrix elements of Phi and
Phi^* give the refined topological vertex C_{lambda mu nu}(t,q) of
Iqbal-Kozcaz-Vafa. With another choice of basis, we recover the refined
topological vertex C_{lambda mu}^nu(q,t) of Awata-Kanno. The gluing factors
appears correctly when we consider any compositions of Phi and Phi^*. The
spectral parameters attached to Fock spaces play the role of the K"ahler
parameters.Comment: 27 page
The Emerging QCD Frontier: The Electron Ion Collider
The self-interactions of gluons determine all the unique features of QCD and
lead to a dominant abundance of gluons inside matter already at moderate .
Despite their dominant role, the properties of gluons remain largely
unexplored. Tantalizing hints of saturated gluon densities have been found in
+p collisions at HERA, and in d+Au and Au+Au collisions at RHIC. Saturation
physics will have a profound influence on heavy-ion collisions at the LHC. But
unveiling the collective behavior of dense assemblies of gluons under
conditions where their self-interactions dominate will require an Electron-Ion
Collider (EIC): a new facility with capabilities well beyond those In this
paper I outline the compelling physics case for +A collisions at an EIC and
discuss briefly the status of machine design concepts. of any existing
accelerator.Comment: 11 pages, 9 figures, prepared for 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions: Quark Matter 2008 (QM2008),
Jaipur, India, 4-10 Feb. 200
Crystalizing the Spinon Basis
The quasi-particle structure of the higher spin XXZ model is studied. We
obtained a new description of crystals associated with the level integrable
highest weight modules in terms of the creation operators
at (the crystaline spinon basis). The fermionic character formulas and
the Yangian structure of those integrable modules naturally follow from this
description. We have also derived the conjectural formulas for the multi
quasi-particle states at .Comment: 25 pages, late
Ultra-Relativistic Magnetic Monopole Search with the ANITA-II Balloon-borne Radio Interferometer
We have conducted a search for extended energy deposition trails left by
ultra-relativistic magnetic monopoles interacting in Antarctic ice. The
non-observation of any satisfactory candidates in the 31 days of accumulated
ANITA-II flight data results in an upper limit on the diffuse flux of
relativistic monopoles. We obtain a 90% C.L. limit of order
10^{-19}/(cm^2-s-sr) for values of Lorentz boost factor 10^{10}<gamma at the
anticipated energy E=10^{16} GeV. This bound is stronger than all previously
published experimental limits for this kinematic range.Comment: updated to version accepted by Phys. Rev.
Wettability characteristics of an Al2O3/SiO2-based ceramic modified with CO2, Nd:YAG, excimer and high-power diode lasers
Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the
surface of an Al2O3/SiO2 based ceramic was found to effect significant changes in the
wettability characteristics of the material. It was observed that interaction with CO2, Nd:YAG
and HPDL radiation reduced the enamel contact angle from 1180 to 310, 340 and 330
respectively. In contrast, interaction with excimer laser radiation resulted an increase in the
contact angle to 1210. Such changes were identified as being due to: (i) the melting and partial
vitrification of the Al2O3/SiO2 based ceramic surface as a result of interaction with CO2,
Nd:YAG HPDL radiation. (ii) the surface roughness of the Al2O3/SiO2 based ceramic
increasing after interaction with excimer laser radiation. (iii) the surface oxygen content of the
Al2O3/SiO2 based ceramic increasing after interaction with CO2, Nd:YAG and HPDL radiation.
The work has shown that the wettability characteristics of the Al2O3/SiO2 based ceramic could
be controlled and/or modified with laser surface treatment. In particular, whether the laser
radiation had the propensity to cause surface melting. However, a wavelength dependance of
the change of the wetting properties could not be deduced from the findings of this work
The LAOG-Planet Imaging Surveys
With the development of high contrast imaging techniques and infrared
detectors, vast efforts have been devoted during the past decade to detect and
characterize lighter, cooler and closer companions to nearby stars, and
ultimately image new planetary systems. Complementary to other observing
techniques (radial velocity, transit, micro-lensing, pulsar-timing), this
approach has opened a new astrophysical window to study the physical properties
and the formation mechanisms of brown dwarfs and planets. I here will briefly
present the observing challenge, the different observing techniques, strategies
and samples of current exoplanet imaging searches that have been selected in
the context of the LAOG-Planet Imaging Surveys. I will finally describe the
most recent results that led to the discovery of giant planets probably formed
like the ones of our solar system, offering exciting and attractive
perspectives for the future generation of deep imaging instruments.Comment: 6 pages, 5 figures, Invited talk of "Exoplanets and disks: their
formation and diversity" conference, 9-12 March 200
Observational Constraints on the Ultra-high Energy Cosmic Neutrino Flux from the Second Flight of the ANITA Experiment
The Antarctic Impulsive Transient Antenna (ANITA) completed its second
long-duration balloon flight in January 2009, with 31 days aloft (28.5 live
days) over Antarctica. ANITA searches for impulsive coherent radio Cherenkov
emission from 200 to 1200 MHz, arising from the Askaryan charge excess in
ultra-high energy neutrino-induced cascades within Antarctic ice. This flight
included significant improvements over the first flight in the payload
sensitivity, efficiency, and a flight trajectory over deeper ice. Analysis of
in-flight calibration pulses from surface and sub-surface locations verifies
the expected sensitivity. In a blind analysis, we find 2 surviving events on a
background, mostly anthropogenic, of 0.97+-0.42 events. We set the strongest
limit to date for 1-1000 EeV cosmic neutrinos, excluding several current
cosmogenic neutrino models.Comment: 6 pages, 5 figures, submitted to Phys. Rev.
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