7,429 research outputs found
A Measurement of the Ratio of the W + 1 Jet to Z + 1 Jet Cross Sections with ATLAS
The measurement of hadronic activity recoiling against W and Z vector bosons
provides an important test of perturbative QCD, as well as a method of
searching for new physics in a model independent fashion. We present a study of
the cross-section ratio for the production of W and Z gauge bosons in
association with exactly one jet Rjet = {\sigma}(W + 1jet)/{\sigma}(Z + 1jet),
in pp collisions at \surds = 7 TeV. The study is performed in the electron and
muon channels with data collected with the ATLAS detector at the LHC. The ratio
Rjet is studied as a function of the cumulative transverse momentum
distribution of the jet. This result can be compared to NLO pQCD calculations
and the prediction from LO matrix element + parton shower generators.Comment: 8 pages, 4 figures, conference proceedings for DPF 201
A semiclassical model of light mesons
The dominantly orbital state description is applied to the study of light
mesons. The effective Hamiltonian is characterized by a relativistic kinematics
supplemented by the usual funnel potential with a mixed scalar and vector
confinement. The influence of two different finite quark masses and potential
parameters on Regge and vibrational trajectories is discussed.Comment: 1 figur
Electromagnetic splitting for mesons and baryons using dressed constituent quarks
Electromagnetic splittings for mesons and baryons are calculated in a
formalism where the constituent quarks are considered as dressed
quasiparticles. The electromagnetic interaction, which contains coulomb,
contact, and hyperfine terms, is folded with the quark electrical density. Two
different types of strong potentials are considered. Numerical treatment is
done very carefully and several approximations are discussed in detail. Our
model contains only one free parameter and the agreement with experimental data
is reasonable although it seems very difficult to obtain a perfect description
in any case.Comment: 14 pages, Revised published versio
Auxiliary field method and analytical solutions of the Schr\"{o}dinger equation with exponential potentials
The auxiliary field method is a new and efficient way to compute approximate
analytical eigenenergies and eigenvectors of the Schr\"{o}dinger equation. This
method has already been successfully applied to the case of central potentials
of power-law and logarithmic forms. In the present work, we show that the
Schr\"{o}dinger equation with exponential potentials of the form can also be analytically solved by using the
auxiliary field method. Formulae giving the critical heights and the energy
levels of these potentials are presented. Special attention is drawn on the
Yukawa potential and the pure exponential one
Tevatron Searches for New Physics with Photons and Jets
The D and CDF experiments have each collected more than 8 fb..1 in Run II of Fermilab\u27s Tevatron, and have many recent search results which use up to 5.2 fb..1. Here I summarize the results of a variety of searches for physics beyond the Standard Model with an emphasis on searches for very exotic phenomena. I will present the status of model-inspired searches for several signatures of supersymmetry, as well as several other searches for several \hidden- valley inspired models, all of which contain photons and jets in the nal state
Sufficient conditions for the existence of bound states in a central potential
We show how a large class of sufficient conditions for the existence of bound
states, in non-positive central potentials, can be constructed. These
sufficient conditions yield upper limits on the critical value,
, of the coupling constant (strength), , of the
potential, , for which a first -wave bound state appears.
These upper limits are significantly more stringent than hitherto known
results.Comment: 7 page
Universality of Regge and vibrational trajectories in a semiclassical model
The orbital and radial excitations of light-light mesons are studied in the
framework of the dominantly orbital state description. The equation of motion
is characterized by a relativistic kinematics supplemented by the usual funnel
potential with a mixed scalar and vector confinement. The influence of finite
quark masses and potential parameters on Regge and vibrational trajectories is
discussed. The case of heavy-light mesons is also presented.Comment: 12 page
Moving boundary approximation for curved streamer ionization fronts: Solvability analysis
The minimal density model for negative streamer ionization fronts is
investigated. An earlier moving boundary approximation for this model consisted
of a "kinetic undercooling" type boundary condition in a Laplacian growth
problem of Hele-Shaw type. Here we derive a curvature correction to the moving
boundary approximation that resembles surface tension. The calculation is based
on solvability analysis with unconventional features, namely, there are three
relevant zero modes of the adjoint operator, one of them diverging;
furthermore, the inner/outer matching ahead of the front has to be performed on
a line rather than on an extended region; and the whole calculation can be
performed analytically. The analysis reveals a relation between the fields
ahead and behind a slowly evolving curved front, the curvature and the
generated conductivity. This relation forces us to give up the ideal
conductivity approximation, and we suggest to replace it by a constant
conductivity approximation. This implies that the electric potential in the
streamer interior is no longer constant but solves a Laplace equation; this
leads to a Muskat-type problem.Comment: 22 pages, 6 figure
A mass formula for light mesons from a potential model
The quark dynamics inside light mesons, except pseudoscalar ones, can be
quite well described by a spinless Salpeter equation supplemented by a Cornell
interaction (possibly partly vector, partly scalar). A mass formula for these
mesons can then be obtained by computing analytical approximations of the
eigenvalues of the equation. We show that such a formula can be derived by
combining the results of two methods: the dominantly orbital state description
and the Bohr-Sommerfeld quantization approach. The predictions of the mass
formula are compared with accurate solutions of the spinless Salpeter equation
computed with a Lagrange-mesh calculation method.Comment: 5 figure
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