19,083 research outputs found
Tau Kinematics from Impact Parameters
The momenta of decay products in the reaction
do not constrain the direction unambiguously. It is shown how the
measurement of tracks of hadrons from semileptonic decays, in particular
their relative impact parameters, allows to resolve this ambiguity.Comment: 4[pag]es, 1 figure available by FAX, TTP93-1
Semileptonic tau decays, structure functions, kinematics and polarisation
The most general angular distribution of two or three meson final states from
semileptonic decays , , ,
, , , of polarized
leptons can be characterized by 16 structure functions. Predictions for
hadronic matrix elements, based on CVC and chiral Lagrangians and their
relations to the structure functions are discussed. Most of them can be
determined in currently ongoing high statistics experiments. Emphasis of the
kinematical analysis is firstly put on decays in
experiments where the neutrino escapes detection and the rest frame
cannot be reconstructed. Subsequently it is shown, how the determination of
hadron tracks in double semileptonic events allows to fully reconstruct the
kinematics. The implications for the spin analysis are indicated.Comment: 12 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/ttp94-27/ttp94-27.ps,
or via www at http://ttpux2.physik.uni-karlsruhe.de/preprints.htm
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-
Measuring sigma(e+ e- --> hadrons) with Tagged Photons at Electron Positron Colliders
A Monte Carlo generator has been constructed to simulate the reaction e+ e-
--> gamma + 2 pions and gamma + 4 pions, where the photon is assumed to be
observed in the detector. Predictions are presented for cms energies of 1GeV,
3GeV and 10GeV, corresponding to the energies of DAPHNE, BEBC and of B-meson
factories. The event rates are sufficiently high to allow for a precise
measurement of R(Q^2) in the region of Q between approximately 1GeV and 2.5GeV.
Estimates for the kinematic breaking of isospin relations between different
channels as a consequence of the mass difference between charged and neutral
pions are given.Comment: Latex, Talk Presented at the Sixth Workshop on Tau Lepton Physics,
Victoria, Canada, The complete paper is also available via the www at
http://www-ttp.physik.uni-karlsruhe.de/Preprints
Exotic Bound State Production at Hadron Colliders
Hadronic production of nonrelativistic boundstates of or
isosinglet quarks D with suppressed weak decays is investigated for LHC and SSC
energies. QCD corrections to production and decay rates are incorporated. Large
rates for final states from are predicted.Comment: 7 pages and 13 figures (figures not includes, can be sent upon
request), TTP93-1
Fermionic and Scalar Corrections for the Abelian Form Factor at Two Loops
Two-loop corrections for the form factor in a massive Abelian theory are
evaluated, which result from the insertion of massless fermion or scalar loops
into the massive gauge boson propagator. The result is valid for arbitrary
energies and gauge boson mass. Power-suppressed terms vanish rapidly in the
high energy region where the result is well approximated by a polynomial of
third order in ln(s/M^2). The relative importance of subleading logarithms is
emphasised.Comment: Latex, 10 pages, 5 figures. B. Feucht is B. Jantzen in later
publications. (The contents of the paper is unchanged.
- …