647 research outputs found
Chern-Simons action for inhomogeneous Virasoro group as an extension of three dimensional flat gravity
We initiate the study of a Chern-Simons action associated to the semi-direct
sum of the Virasoro algebra with its coadjoint representation. This model
extends the standard Chern-Simons formulation of three dimensional flat gravity
and is similar to the higher-spin extension of three dimensional anti-de Sitter
or flat gravity. The extension can also be constructed for the exotic but not
for the cosmological constant deformation of flat gravity.Comment: 15 pages. Version to appear in J. of Math. Phy
First principles simulations of 2D Cu superlattices on the MgO(001) surface
First principles slab simulations of copper 2D superlattices of different densities on the perfect MgO(0 0 1) surface are performed using the DFT method as implemented into the CRYSTAL98 computer code. In order to clarify the nature of interfacial bonding, we consider regular 1/4, 1/2 and I monolayer (ML) coverages and compare results of our calculations with various experimental and theoretical data. Our general conclusion is that the physical adhesion associated with a Cu polarization and charge redistribution gives the predominant contribution to the bonding of the regular Cu 2D layer on the MgO(0 0 1) surface. (C) 2003 Elsevier B.V. All rights reserved
Simulating spin-3/2 particles at colliders
Support for interactions of spin-3/2 particles is implemented in the
FeynRules and ALOHA packages and tested with the MadGraph 5 and CalcHEP event
generators in the context of three phenomenological applications. In the first,
we implement a spin-3/2 Majorana gravitino field, as in local supersymmetric
models, and study gravitino and gluino pair-production. In the second, a
spin-3/2 Dirac top-quark excitation, inspired from compositness models, is
implemented. We then investigate both top-quark excitation and top-quark
pair-production. In the third, a general effective operator for a spin-3/2
Dirac quark excitation is implemented, followed by a calculation of the angular
distribution of the s-channel production mechanism.Comment: 20 pages, 7 figure
Temperature Control of Sequential Nucleation-Growth Mechanisms in Hierarchical Supramolecular Polymers
Two-Scale Kirchhoff Theory: Comparison of Experimental Observations With Theoretical Prediction
We introduce a non-perturbative two scale Kirchhoff theory, in the context of
light scattering by a rough surface. This is a two scale theory which considers
the roughness both in the wavelength scale (small scale) and in the scales much
larger than the wavelength of the incident light (large scale). The theory can
precisely explain the small peaks which appear at certain scattering angles.
These peaks can not be explained by one scale theories. The theory was assessed
by calculating the light scattering profiles using the Atomic Force Microscope
(AFM) images, as well as surface profilometer scans of a rough surface, and
comparing the results with experiments. The theory is in good agreement with
the experimental results.Comment: 6 pages, 8 figure
A new application of reduced Rayleigh equations to electromagnetic wave scattering by two-dimensional randomly rough surfaces
The small perturbations method has been extensively used for waves scattering
by rough surfaces. The standard method developped by Rice is difficult to apply
when we consider second and third order of scattered fields as a function of
the surface height. Calculations can be greatly simplified with the use of
reduced Rayleigh equations, because one of the unknown fields can be
eliminated. We derive a new set of four reduced equations for the scattering
amplitudes, which are applied to the cases of a rough conducting surface, and
to a slab where one of the boundary is a rough surface. As in the
one-dimensional case, numerical simulations show the appearance of enhanced
backscattering for these structures.Comment: RevTeX 4 style, 38 pages, 16 figures, added references and comments
on the satellites peak
Les Houches 2013: Physics at TeV Colliders: Standard Model Working Group Report
This Report summarizes the proceedings of the 2013 Les Houches workshop on
Physics at TeV Colliders. Session 1 dealt primarily with (1) the techniques for
calculating standard model multi-leg NLO and NNLO QCD and NLO EW cross sections
and (2) the comparison of those cross sections with LHC data from Run 1, and
projections for future measurements in Run 2.Comment: Proceedings of the Standard Model Working Group of the 2013 Les
Houches Workshop, Physics at TeV Colliders, Les houches 3-21 June 2013. 200
page
Z' signals in polarised top-antitop final states
We study the sensitivity of top-antitop samples produced at all energy stages
of the Large Hadron Collider (LHC) to the nature of an underlying Z' boson, in
presence of full tree level standard model (SM) background effects and relative
interferences. We concentrate on differential mass spectra as well as both
spatial and spin asymmetries thereby demonstrating that exploiting combinations
of these observables will enable one to distinguish between sequential Z's and
those pertaining to Left-Right symmetric models as well as E6 inspired ones,
assuming realistic final state reconstruction efficiencies and error estimates.Comment: 21 pages, 6 colour figures, 10 table
Les Houches 2015: Physics at TeV colliders - new physics working group report
We present the activities of the 'New Physics' working group for the 'Physics
at TeV Colliders' workshop (Les Houches, France, 1-19 June, 2015). Our report
includes new physics studies connected with the Higgs boson and its properties,
direct search strategies, reinterpretation of the LHC results in the building
of viable models and new computational tool developments. Important signatures
for searches for natural new physics at the LHC and new assessments of the
interplay between direct dark matter searches and the LHC are also considered.Comment: Proceedings of the New Physics Working Group of the 2015 Les Houches
Workshop, Physics at TeV Colliders, Les Houches 1-19 June 2015. 197 page
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