arXiv subjects

J. H. K"uhn

Publications and source records attributed to J. H. K"uhn.

4 recordsLinked to original sources

arXiv2001

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.

hep-ph↗

arXiv1994

Structure Functions and Distributions in Semileptonic Tau Decays

Semileptonic decays of polarized $τ$ leptons are investigated. The most general angular distribution of three meson final states ($τ\rightarrow ππν,\,Kπν,\, πππν,\\ \,Kππν,\, KKπν,\, KKKν,\, ηππν,\,\ldots{}$) is discussed. It is shown, that the most general distribution can be characterized by 16 structure functions, most of which can be determined in currently ongoing high statistics experiments. Emphasis is put on $τ$ decays in $e^{+}e^{-}$ experiments where the neutrino escapes detection and the $τ$ rest frame cannot be reconstructed. The structure of the hadronic matrix elements, based on CVC and chiral lagrangians, is discussed.

hep-ph↗

arXiv1993

Exotic Bound State Production at Hadron Colliders

Hadronic production of nonrelativistic boundstates of $b^{\prime}$ 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 $η_{b^{\prime}}\rightarrow HZ$ are predicted.

hep-ph↗

arXiv1993

QCD Corrections to Toponium Production at Hadron Colliders

Toponium production at future hadron colliders is investigated. Perturbative QCD corrections to the production cross section for gluon fusion are calculated as well as the contributions from gluon-quark and quark-antiquark collisions to the total cross section. The dependence on the renormalization and factorization scales and on the choice of the parton distribution functions is explored. QCD corrections to the branching ratio of $η_{t}$ into $γγ$ are included and the two-loop QCD potential is used to predict the wave function at the origin. The branching ratio of $η_{t}$ into $γZ$, $ZZ$, $HZ$ and $WW$ is compared with the $γγ$ channel.

hep-ph↗