29,086 research outputs found
Prospect for the Higgs searches with the ATLAS detector
The investigation of the electroweak symmetry breaking is one of the primary
tasks of the experiments at the CERN Large Hadron Collider (LHC). The potential
of the ATLAS experiment for the discovery of the Higgs boson(s) in Standard
Model and Minimal Supersymmetric Standard Model is presented, with emphasis on
studies which have been completed recently.Comment: Presented at Cracow Epiphany Conference on Hadron Interactions at the
Dawn of the LHC, dedicated to memory of J. Kwiecinski, Krakow, Poland, 5-7
January 2009, 22page
Separating Electroweak and Strong interactions in Drell-Yan processes at LHC: leptons angular distributions and reference frames
Among the physics goals of LHC experiments, precision tests of the Standard
Model in the Strong and Electroweak sectors play an important role. Because of
nature of the proton-proton processes, observables based on the measurement of
the direction and energy of leptons provide the most precise signatures. In the
present paper, we concentrate on the angular distribution of Drell-Yan process
leptons, in the lepton-pair rest-frame. The vector nature of the intermediate
state imposes that distributions are to a good precision described by spherical
polynomials of at most second order.
We show that with the proper choice of the coordinate frames, only one
coefficient in this polynomial decomposition remains sizable, even in the
presence of one or two high jets. The necessary stochastic choice of the
frames relies on probabilities independent from any coupling constants.
This remains true when one or two partons accompany the lepton pairs. In this
way electroweak effects can be better separated from strong interaction ones
for the benefit of the interpretation of the measurements.
Our study exploits properties of single gluon emission matrix elements which
are clearly visible if a conveniently chosen form of their representation is
used. We rely also on distributions obtained from matrix element based Monte
Carlo generated samples of events with two leptons and up to two additional
partons in test samples. Incoming colliding protons' partons are distributed
accordingly to PDFs and are strictly collinear to the corresponding beams.Comment: 22 pages 9 figure
Discrete vs. functional based data to analyze countermovement jump performance
While discrete point analysis (DPA) (e.g. peak power) is by far the most common method of analyzing movement data, it may have significant limitations because it ignores the vast majority of a signal’s data. In response, there has been a small but growing use of methods, such as functional data analysis (FDA), which allow an investigation of the underlying structure of the continuous signal and may therefore provide a more powerful analysis. However, a direct comparison between DPA and FDA has not been previously reported
Diagonalization of a bosonic quadratic form using CCM: Application on a system with two interpenetrating square lattice antiferromagnets
While the diagonalization of a quadratic bosonic form can always be done
using a Bogoliubov transformation, the practical implementation for systems
with a large number of different bosons is a tedious analytical task. Here we
use the coupled cluster method (CCM) to exactly diagonalise such complicated
quadratic forms. This yields to a straightforward algorithm which can easily be
implemented using computer algebra even for a large number of different bosons.
We apply this method on a Heisenberg system with two interpenetrating square
lattice antiferromagnets, which is a model for the quasi 2D antiferromagnet
Ba_2Cu_3O_4Cl_2. Using a four-magnon spin wave approximation we get a
complicated Hamiltonian with four different bosons, which is treated with CCM.
Results are presented for magnetic ground state correlations.Comment: 4 pages, 2 Postscript figures, to be published in acta physica
polonica A (European Conference 'Physics of Magnetism 99'
The tauola-photos_F environment for versioning the TAUOLA and PHOTOS packages
We present the system for versioning two packages: the TAUOLA of tau lepton
decay and PHOTOS for radiative corrections in decays. The following features
can be chosen in automatic or semi-automatic way: (1) format of the common
block HEPEVT; (2) version of the physics input (for TAUOLA): as published, as
initialized by CLEO collaboration, as initialized by ALEPH collaboration (it is
suggested to use this version only with the help of the collaboration advice);
(3) type of application: stand-alone, universal interface through HEPEVT,
interface for KKMC Monte Carlo; (4) random number generators; (5) compiler
options.Comment: nine pages, late
The spin 1/2 Heisenberg star with frustration II: The influence of the embedding medium
We investigate the spin 1/2 Heisenberg star introduced in J. Richter and A.
Voigt, J. Phys. A: Math. Gen. {\bf 27}, 1139 (1994). The model is defined by
; , . In extension to the Ref. we consider a more general
describing the properties of the spins surrounding the
central spin . The Heisenberg star may be considered as an essential
structure element of a lattice with frustration (namely a spin embedded in a
magnetic matrix ) or, alternatively, as a magnetic system with a
perturbation by an extra spin. We present some general features of the
eigenvalues, the eigenfunctions as well as the spin correlation of the model. For being a linear chain, a square
lattice or a Lieb-Mattis type system we present the ground state properties of
the model in dependence on the frustration parameter .
Furthermore the thermodynamic properties are calculated for being a
Lieb--Mattis antiferromagnet.Comment: 16 pages, uuencoded compressed postscript file, accepted to J. Phys.
A: Math. Ge
Y su análisis estratigráfico con 3 ilustraciones
Extracto de Notas y Comunicaciones del Instituto Geológico y Minero de Españ
Preparation and photoemission investigation of bulk-like a-Mn films on W(110)
We report the successful stabilization of a thick bulk-like, distorted
-Mn film with (110) orientation on a W(110) substrate. The observed
overstructure for the Mn film with respect to the original W(110)
low-energy electron diffraction pattern is consistent with the presented
structure model. The possibility to stabilize such a pseudomorphic Mn film is
supported by density functional total energy calculations. Angle-resolved
photoemission spectra of the stabilized -Mn(110) film show weak
dispersions of the valence band electronic states in accordance with the large
unit cell.Comment: 11 pages; 5 figure
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