455 research outputs found
Lower Body Kinematics Do Not Differ Between Flat Ground and Mound Baseball Throwing
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Upper Body Kinetics has No Difference for Mound and Flat Ground Throwing
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Singular behaviour of the electromagnetic field
The singularities of the electromagnetic field are derived to include all the
point-like multipoles representing an electric charge and current distribution.
Firstly derived in the static case, the result is generalized to the dynamic
one. We establish a simple procedure for passing from the first, to the second
case.Comment: Latex, 21.pages, no figure
Phase-plane analysis of Friedmann-Robertson-Walker cosmologies in Brans-Dicke gravity
We present an autonomous phase-plane describing the evolution of
Friedmann-Robertson-Walker models containing a perfect fluid (with barotropic
index gamma) in Brans-Dicke gravity (with Brans-Dicke parameter omega). We find
self-similar fixed points corresponding to Nariai's power-law solutions for
spatially flat models and curvature-scaling solutions for curved models. At
infinite values of the phase-plane variables we recover O'Hanlon and Tupper's
vacuum solutions for spatially flat models and the Milne universe for negative
spatial curvature. We find conditions for the existence and stability of these
critical points and describe the qualitative evolution in all regions of the
(omega,gamma) parameter space for 0-3/2. We show that the
condition for inflation in Brans-Dicke gravity is always stronger than the
general relativistic condition, gamma<2/3.Comment: 24 pages, including 9 figures, LaTe
Random matrix theory and
We suggest that the spectral properties near zero virtuality of three
dimensional QCD, follow from a Hermitean random matrix model. The exact
spectral density is derived for this family of random matrix models both for
even and odd number of fermions. New sum rules for the inverse powers of the
eigenvalues of the Dirac operator are obtained. The issue of anomalies in
random matrix theories is discussed.Comment: 10p., SUNY-NTG-94/1
Correction Factors for Reactions involving Quark-Antiquark Annihilation or Production
In reactions with production or annihilation, initial-
and final-state interactions give rise to large corrections to the lowest-order
cross sections. We evaluate the correction factor first for low relative
kinetic energies by studying the distortion of the relative wave function. We
then follow the procedure of Schwinger to interpolate this result with the
well-known perturbative QCD vertex correction factors at high energies, to
obtain an explicit semi-empirical correction factor applicable to the whole
range of energies. The correction factor predicts an enhancement for
in color-singlet states and a suppression for color-octet states, the effect
increasing as the relative velocity decreases. Consequences on dilepton
production in the quark-gluon plasma, the Drell-Yan process, and heavy quark
production processes are discussed.Comment: 25 pages (REVTeX), includes 2 uuencoded compressed postscript figure
Searches for phenomena beyond the Standard Model at the LHC with the ATLAS and CMS detectors
The LHC has delivered several fb-1 of data in spring and summer 2011, opening
new windows of opportunity for discovering phenomena beyond the Standard Model.
A summary of the searches conducted by the ATLAS and CMS experiments based on
about 1 fb-1 of data is presented.Comment: Presented at Lepton-Photon 2011, Mumbai, India; 10 pages, 11 figure
Qualitative properties of scalar-tensor theories of Gravity
The qualitative properties of spatially homogeneous stiff perfect fluid and
minimally coupled massless scalar field models within general relativity are
discussed. Consequently, by exploiting the formal equivalence under conformal
transformations and field redefinitions of certain classes of theories of
gravity, the asymptotic properties of spatially homogeneous models in a class
of scalar-tensor theories of gravity that includes the Brans-Dicke theory can
be determined. For example, exact solutions are presented, which are analogues
of the general relativistic Jacobs stiff perfect fluid solutions and vacuum
plane wave solutions, which act as past and future attractors in the class of
spatially homogeneous models in Brans-Dicke theory.Comment: 19 page
V,W and X in Technicolour Models
Light techni-fermions and pseudo Goldstone bosons that contribute to the
electroweak radiative correction parameters V,W and X may relax the constraints
on technicolour models from the experimental values of the parameters S and T.
Order of magnitude estimates of the contributions to V,W and X from light
techni-leptons are made when the the techni-neutrino has a small Dirac mass or
a large Majorana mass. The contributions to V,W and X from pseudo Goldstone
bosons are calculated in a gauged chiral Lagrangian. Estimates of V,W and X in
one family technicolour models suggest that the upper bounds on S and T should
be relaxed by between 0.1 and 1 depending upon the precise particle spectrum.Comment: 19 pages + 2 pages of ps figs, SWAT/1
Stars in five dimensional Kaluza Klein gravity
In the five dimensional Kaluza Klein (KK) theory there is a well known class
of static and electromagnetic--free KK--equations characterized by a naked
singularity behavior, namely the Generalized Schwarzschild solution (GSS). We
present here a set of interior solutions of five dimensional KK--equations.
These equations have been numerically integrated to match the GSS in the
vacuum. The solutions are candidates to describe the possible interior perfect
fluid source of the exterior GSS metric and thus they can be models for stars
for static, neutral astrophysical objects in the ordinary (four dimensional)
spacetime.Comment: 15 pages, 8 figures. To be published in EPJ
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