9,307 research outputs found
Meteoroid sensing apparatus having a coincidence network connected to a pair of capacitors Patent
Capacitor sandwich structure containing metal sheets of known thickness for counting penetration rates of meteoroid
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
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
Improved sensor counts micrometeoroid penetrations
A sensor, consisting of a thin dual-capacitor assembly with an outer film of thermal-control material, is used to detect micrometeoroid particles. A coincidence counting circuit is used to count the penetrations
Treading in Mortimer's footsteps: the geochemical cycling of iron and manganese in Esthwaite water
A study of the geochemical cycling of iron and manganese in a seasonally stratified lake, Esthwaite water is described. This work is based on speculative ideas on environmental redox chemistry of iron which were proposed by C.H. Mortimer in the 1940's. These observations have been verified and some speculations confirmed, along with a new understanding of the manganese cycle, and detailed information on the particulate forms of both iron and manganese. Details on the mechanisms and transformations of iron have also emerged
QCD and Monte Carlo event generators
Shower Monte Carlo event generators have played an important role in particle
physics. Modern experiments would hardly be possible without them. In this talk
I discuss how QCD physics is incorporated into the mathematical structure of
these programs and I outline recent developments including matching between
events with different numbers of hard jets and the inclusion of next-to-leading
order effects.Comment: Plenary talk by D. Soper at XIV Workshop on Deep Inelastic Scattering
(DIS2006
Parton distribution functions in the context of parton showers
When the initial state evolution of a parton shower is organized according to
the standard "backward evolution'' prescription, ratios of parton distribution
functions appear in the splitting probabilities. The shower thus organized
evolves from a hard scale to a soft cutoff scale. At the end of the shower, one
expects that only the parton distributions at the soft scale should affect the
results. The other effects of the parton distributions should have cancelled.
This means that the kernels for parton evolution should be related to the
shower splitting functions. If the initial state partons can have non-zero
masses, this requires that the evolution kernels cannot be the usual MSbar
kernels. We work out what the parton evolution kernels should be to match the
shower evolution contained in the parton shower event generator Deductor, in
which the b and c quarks have non-zero masses.Comment: 33 pages, 6 figure
On the transverse momentum in Z-boson production in a virtuality ordered parton shower
Cross sections for physical processes that involve very different momentum
scales in the same process will involve large logarithms of the ratio of the
momentum scales when calculated in perturbation theory. One goal of
calculations using parton showers is to sum these large logarithms. We ask
whether this goal is achieved for the transverse momentum distribution of a
Z-boson produced in hadron-hadron collisions when the shower is organized with
higher virtuality parton splittings coming first, followed successively by
lower virtuality parton splittings. We find that the virtuality ordered shower
works well in reproducing the known QCD result.Comment: 60 pages with three figure
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