12,983 research outputs found
A generatingfunctionology approach to a problem of Wilf
Wilf posed the following problem: determine asymptotically as
the probability that a randomly chosen part size in a randomly chosen
composition of n has multiplicity m. One solution of this problem was given by
Hitczenko and Savage. In this paper, we study this question using the
techniques of generating functions and singularity analysis.Comment: 12 page
Giant anharmonicity suppresses superconductivity in AlH under pressure
The anharmonic self energy of two zone boundary phonons were computed to
lowest order for AlH in the structure at 110 GPa. The
wavevector and branch index corresponding to these modes are situated in a
region of phase space providing most of the electron-phonon coupling. The self
energies are found to be very large and the anharmonic contribution to the
linewidth of one of the modes studied could be distinguished from the
electron-phonon linewidth. It is found that anharmonicity suppresses the
electron-phonon coupling parameter , providing a possible explanation
for the disagreement between experiment and previous theoretical studies of
superconductivity in this system.Comment: 10 pages, 4 figure
The Software behind the Higgs Boson Discovery
In this column, David Rousseau describes the enormous software development effort associated with teasing out evidence for the elusive Higgs boson, a cornerstone of the Standard Model. In keeping with previous Impact columns, everything about this is huge but the application is unique
Compressive Pattern Matching on Multispectral Data
We introduce a new constrained minimization problem that performs template
and pattern detection on a multispectral image in a compressive sensing
context. We use an original minimization problem from Guo and Osher that uses
minimization techniques to perform template detection in a multispectral
image. We first adapt this minimization problem to work with compressive
sensing data. Then we extend it to perform pattern detection using a formal
transform called the spectralization along a pattern. That extension brings out
the problem of measurement reconstruction. We introduce shifted measurements
that allow us to reconstruct all the measurement with a small overhead and we
give an optimality constraint for simple patterns. We present numerical results
showing the performances of the original minimization problem and the
compressed ones with different measurement rates and applied on remotely sensed
data.Comment: Published in IEEE Transactions on Geoscience and Remote Sensin
Little Higgs studies in ATLAS
Study of the possible discovery in Atlas of the new particles predicted by Little Higgs models are presented. Different heavy bosons W_H/Z_H/A_H final states have been studied, with, when relevant, two Higgs mass hypotheses mH=120 GeV and mH=200 GeV. The heavy top T, and the new higgs boson phi++ have also been searched for. The discovery potential of ATLAS is shown to cover a significant portion of the parameter space. This paper is part of the 2006 CERN yellow report : CP studies and non-standard Higgs physics
Propositions pour la masterisation
Sans porter de jugement sur la rĂ©forme de masterisation de la formation des maĂźtres en cours, cette libre opinion, s\u27appuyant sur des enquĂȘtes menĂ©es Ă l\u27Ă©chelle locale et nationale, propose des outils de travail collaboratif pour rompre avec la taylorisation des tĂąches entre les diffĂ©rents acteurs de la formation des maĂźtres (universitĂ©s, IUFM, rectorat, Ă©tablissements du secondaire) et tendre vers une logique de rĂ©seau de contribution
Utilisation dâune manette de jeu vidĂ©o pour des expĂ©riences de mĂ©canique
Dans cet article sont donnĂ©es les informations pratiques nĂ©cessaires Ă la mise en oeuvre, simple, originale et peu coĂ»teuse, d\u27un contrĂŽleur de jeu vidĂ©o pour mesurer des accĂ©lĂ©rations. Quelques idĂ©es d\u27expĂ©riences utilisant ce dispositif sont ensuite indiquĂ©es. L\u27intĂ©rĂȘt pĂ©dagogique d\u27une telle dĂ©marche dans le cadre d\u27un enseignement sur la notion de capteur est enfin discutĂ©
Using off-diagonal confinement as a cooling method
In a recent letter [Phys. Rev. Lett. 104, 167201 (2010)] we proposed a new
confining method for ultracold atoms on optical lattices, based on off-diagonal
confinement (ODC). This method was shown to have distinct advantages over the
conventional diagonal confinement (DC) that makes use of a trapping potential,
including the existence of pure Mott phases and highly populated condensates.
In this paper we show that the ODC method can also lead to temperatures that
are smaller than with the conventional DC method, depending on the control
parameters. We determine these parameters using exact diagonalizations for the
hard-core case, then we extend our results to the soft-core case by performing
quantum Monte Carlo (QMC) simulations for both DC and ODC systems at fixed
temperatures, and analysing the corresponding entropies. We also propose a
method for measuring the entropy in QMC simulations.Comment: 6 pages, 6 figure
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