6,333 research outputs found
V-a Tests Through Leptons from Polarised Top Quarks
Angular-energy distributions are studied for charged leptons and neutrinos
from the decays of polarised top quarks. A small admixture of V+A interactions
is incorporated. The polarisation dependent part of the neutrino distribution
which can be measured experimentally through the missing momentum is
particularly sensitive towards deviations from the V-A structure. This result
remains unaffected by QCD corrections which, however, cannot be neglected in a
quantitative analysis.Comment: 10 pages, LaTex (uses epsf.sty, 2 figures appended as uuencoded ps
files). A complete postscript file, including figures, is available via
anonymous ftp at ttpux2.physik.uni-karlsruhe.de (129.13.102.139) as
/ttp94-4/ttp94-4.ps, Local preprint# TTP94-
QCD Corrections to Electroweak Annihilation Decays of Superheavy Quarkonia
QCD corrections to all the allowed decays of superheavy groundstate quarkonia
into electroweak gauge and Higgs bosons are presented. For quick estimates,
approximations that reproduce the exact results within less than at worst two
percent are also given.Comment: 20 pages RevTeX, 9 figures. The complete paper, including figures, is
also available via anonymous ftp at (129.13.102.139) as
ftp://ttpux2.physik.uni-karlsruhe.de/ttp95-05/ttp95-05.ps, or via www at
http://ttpux2.physik.uni-karlsruhe.de/cgi-bin/preprints
Hadron Radiation in Leptonic Decays
The rate for the final state radiation of hadrons in leptonic decays is
evaluated, using as input experimental data for in
the low energy region. Configurations with a lepton pair of large and a
hadronic state of low invariant mass are dominant. A relative rate
is calculated. This
result is about twice the prediction based on a parton model calculation with a
quark mass of MeV. The rate for secondary production of heavy quarks is
calculated in the same formalism.Comment: 7 pages, LaTex (uses epsf.sty, 2 figures appended as uuencoded eps
files). Errors of some numerical values corrected. Conclusions are not
affected by these modification
Comment on the Average Momentum of Top Quarks in the Threshold Region
The behavior of the momentum distribution of top quarks in the threshold
region is investigated. The qualitative behavior, in particular the dependence
of the average momentum on the strong coupling constant can be understood from
analytical calculations for the Coulomb potential. Ambiguities in the relation
between the excitation curve and the top mass are addressed.Comment: Univ. of Karlsruhe preprint TTP93-31, LaTeX, 6 pages including two
figures (uses epsf) appended as uuencoded postscript fil
Polarization in Top Quark Pair Production near Threshold
The polarization dependent momentum distributions of top quarks and their
decay products are calculated for production at future
colliders with polarized beams. The Green function formalism is applied to this
reaction near energy threshold. The Lippmann--Schwinger equations for the
-wave and -wave Green functions are solved numerically for the QCD
chromostatic potential given by the two-loop formula at large momentum
transfers and Richardson ansatz at intermediate and small ones. It is
demonstrated that for the longitudinally polarized electron beam an optimally
polarized sample of top quarks can be produced.Comment: 11 pages, LaTex (uses epsf.sty, 3 ps-figures appended as extra
uuencoded file). The complete paper, including figures, is also available via
anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ttp94-28/ttp94-28.ps,
or via www at http://ttpux2.physik.uni-karlsruhe.de/preprints.htm
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