1,096 research outputs found
QCD Theory
Quantum Chromodynamics is an established part of the Standard Model and an
essential part of the toolkit for searching for new physics at high-energy
colliders. I present a status report on the theory of QCD and review some of
the important developments in the past year.Comment: 10 pages, 11 figures, plenary talk presented at ICHEP04, Beijing,
China, August 200
Forward jets and forward -boson production at hadron colliders
In this talk we give a short review of forward jets and forward -boson
production at hadron colliders, in view of the extraction of footprints of BFKL
physics. We argue that at Tevatron energies, dijet production at large rapidity
intervals is still subasymptotic with respect to the BFKL regime, thus the
cross section is strongly dependent on the various cuts applied in the
experimental setup. In addition, the choice of equal transverse momentum cuts
on the tagging jets makes the cross section dependent on large logarithms of
non-BFKL origin, and thus may spoil the BFKL analysis. For vector boson
production in association with two jets, we argue that the configurations that
are kinematically favoured tend to have the vector boson forward in rapidity.
Thus jet production lends itself naturally to extensions to the
high-energy limit.Comment: LaTeX, JHEP style, 10 pages, 3 figures. Based on a talk at EPS2001,
Budapest, Hungar
Additional Soft Jets in Production at the Tevatron \pp Collider
A large fraction of top quark events in \pp collisions at 1.8\ \TeV will
contain additional soft hadronic jets from gluon bremsstrahlung off the quarks
and gluons in the hard processes \qq, gg \to \tt \to \bb \ww. These extra
jets can cause complications when attempting to reconstruct from the
invariant mass of combinations of final-state quarks and leptons. We show how
such soft radiation cannot be unambiguously associated with either
initial-state radiation or or with final-state radiation off the quarks.
The top quarks can radiate too, and in fact the pattern of radiation has a very
rich structure, which depends on the orientation of the final-state particles
with respect to each other and with respect to the beam. We calculate the full
radiation pattern of soft jets in the soft gluon approximation and compare with
several approximate forms which are characteristic of parton shower Monte
Carlos. The implications for top mass measurements are discussed.Comment: plain LaTeX, 13 pages plus 9 figures included as a separate uuencoded
file (or avail. from authors); DTP/94/60, UR-136
W + gamma + jet production as a test of the electromagnetic couplings of W at LHC and SSC
The reaction is considered at
centre-of-mass energies and 40\;\tev, including anomalous
three-gauge-boson couplings and . The possibility of
obtaining limits on these quantities by comparison with the standard model is
investigated. The radiation zero properties of the subprocess matrix elements
are studied. CERN-TH.6753/92, DTP/92/92.Comment: Latex. 5 figures available (EPS files) on reques
Profile of the U 5f magnetization in U/Fe multilayers
Recent calculations, concerning the magnetism of uranium in the U/Fe
multilayer system have described the spatial dependence of the 5f polarization
that might be expected. We have used the x-ray resonant magnetic reflectivity
technique to obtain the profile of the induced uranium magnetic moment for
selected U/Fe multilayer samples. This study extends the use of x-ray magnetic
scattering for induced moment systems to the 5f actinide metals. The spatial
dependence of the U magnetization shows that the predominant fraction of the
polarization is present at the interfacial boundaries, decaying rapidly towards
the center of the uranium layer, in good agreement with predictions.Comment: 7 pages, 6 figure
The non-ballistic superluminal motion in the plane of the sky-II
The model of non-ballistic jet motion proposed in 2008 provides a simple
explanation to the inward jet motion and bent jet. Recently, evidences of such
a non-radial motion increase rapidly, and more complicated morphologies appear.
On the other hand, the ballistic plus precession model likely holds in majority
samples of jet motion. This paper discusses the relationship between the
ballistic and non-ballistic model of jet motion, which suggests that the
interaction of ejectors with ambient matter can produce knots at different
stages of evolution and hence different separations to the core. And as a jet
precesses, knots produced between the core and the deceleration radius result
in spiral pattern expected by the model of ballistic plus precession; and knots
generated at the deceleration radius display non-radial motion such as bent jet
or oscillation of ridge-line. This paper develops the first non-ballistic model
in four aspects. Firstly, it provides a numerical simulation to the production
of multi-knot for a precessing jet. Secondly, it fits the precession behavior
of multi-knot and interprets the oscillation of ridge lines like S5 1803+784.
Thirdly, it gives an unified interpretation to the bent jet applicable to both
multi-knot and single knot. And fourthly, the problem of very large numbers of
observed outward motions as opposed to the inward ones is addressed in a new
scope.Comment: 9 pages, 6 figures, accepted by MNRA
The polarizability model for ferroelectricity in perovskite oxides
This article reviews the polarizability model and its applications to
ferroelectric perovskite oxides. The motivation for the introduction of the
model is discussed and nonlinear oxygen ion polarizability effects and their
lattice dynamical implementation outlined. While a large part of this work is
dedicated to results obtained within the self-consistent-phonon approximation
(SPA), also nonlinear solutions of the model are handled which are of interest
to the physics of relaxor ferroelectrics, domain wall motions, incommensurate
phase transitions. The main emphasis is to compare the results of the model
with experimental data and to predict novel phenomena.Comment: 55 pages, 35 figure
Review of Environmental Morphine Identifications: Worldwide Occurrences and Responses of Authorities
Opium poppies grow wild worldwide, and testing for morphine is now highly sensitive. Currently, many authorities worldwide do not pursue urinary morphine concentrations of less than 100 ng /ml. This is because such low urinary morphine concentrations are likely to be environmental morphine identifications (EMIs) and are also unlikely to be associated with pharmacological responses
- …