7,962 research outputs found
Next-to-leading order numerical calculations in Coulomb gauge
Calculations of observables in quantum chromodynamics can be performed using
a method in which all of the integrations, including integrations over virtual
loop momenta, are performed numerically. We use the flexibility inherent in
this method in order to perform next-to-leading order calculations for event
shape variables in electron-positron annihilation in Coulomb gauge. The use of
Coulomb gauge provides the potential to go beyond a purely order alpha_s^2
calculation by including, for instance, renormalon or parton showering effects.
We expect that the approximations needed to include such effects at all orders
in alpha_s will be simplest in a gauge in which unphysically polarized gluons
do not propagate over long distances.Comment: 36 pages with 7 figure
QCD Calculations by Numerical Integration
Calculations of observables in Quantum Chromodynamics are typically performed
using a method that combines numerical integrations over the momenta of final
state particles with analytical integrations over the momenta of virtual
particles. I discuss a method for performing all of the integrations
numerically.Comment: 9 pages including 2 figures. RevTe
Choosing integration points for QCD calculations by numerical integration
I discuss how to sample the space of parton momenta in order to best perform
the numerical integrations that lead to a calculation of three jet cross
sections and similar observables in electron-positron annihilation.Comment: 25 pages with 8 figure
Diffraction in DIS and Elsewhere
I review some of the results presented in the working group on diffraction at
DIS97, with a particular emphasis on the theory of diffractive hard scattering.Comment: Talk at DIS97 Conference, Chicago, April 1997. Eleven pages including
nine figure
Radical re-appraisal of water structure in hydrophilic confinement
The structure of water confined in MCM41 silica cylindrical pores is studied
to determine if confined water really is simply a version of the bulk liquid
which can be substantially supercooled without crystallisation. A combination
of total neutron scattering from the porous silica, both wet and dry,and
computer simulation using a realistic model of the scattering substrate isused.
The water in the pore is divided into three regions: core, interfacial and
overlap. The average local densities of water in these simulations are found to
be about 20% lower than bulk water density, while the density in the core
region is below, but closer to, the bulk density. There is a decrease in both
local and core densities when the temperature is lowered from 298K to 210K. The
radical proposal is made here that water in hydrophilic confinement is under
significant tension, around -100MPa, inside the pore
Basics of QCD Perturbation Theory: TASI 2000
This is an introduction to the use of QCD perturbation theory, emphasizing
generic features of the theory that enable one to separate short-time and
long-time effects. I also cover some important classes of applications:
electron-positron annihilation to hadrons, deeply inelastic scattering, and
hard processes in hadron-hadron collisions.Comment: Lectures at TASI summer school, June 200
An interactive approach to learning economics: The WinEcon package
Under the TLTP initiative, the Economics Consortium is developing an interactive computerâbased learning package called WinEcon. The package is directed at firstâyear economics undergraduates, particularly those taking economics as a supplementary course. Using recent technological developments, the aim is both to facilitate a further increase in student numbers without a proportionate increase in teaching staff, and to provide a better method of student learning. Some key elements of WinEcon are set out in this paper and demonstrated by screens produced at Leicester University. Methods of presenting textual information that give the user control over accessing it are described. For learning difficult concepts, a visual active learning approach is discussed. It involves user interaction and stepâbyâstep analysis. The importance of flexibility and choice is emphasized, and the capacity of the computer to assist in deepening and consolidating learning is shown
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