Some Remarks on Realization of Simplicial Algebras in Cat

In this paper we discuss why the passage from simplicial algebras over a Cat operad to algebras over that operad involves apparently unavoidable technicalities.Comment: 16 page

The annihilation of virtual photons into pseudoscalar mesons

We investigate the possibility to constrain the pion distribution amplitude from the gamma* gamma* -> pi transition. For a surprisingly large range in the two photon virtualities we find that the transition form factor is essentially independent of the distribution amplitude. This in turn entails a parameter-free prediction of QCD. The gamma* gamma* -> eta, eta' form factors are also briefly discussed. We estimate that experimental studies might be feasible at the existing e+ e- experiments BaBar, Belle, and CLEO.Comment: 22 pages latex, 9 figure

The Extraction of the Gluon Density from Jet Production in Deeply Inelastic Scattering

The prospects of a direct extraction of the proton's gluon density in next-to-leading order via jet rates in deeply inelastic scattering are studied. The employed method is based on the Mellin transform, and can be applied, in principle, to all infra-red-safe observables of hadronic final states. We investigate the dependence of the error band on the extracted gluon distribution on the statistical and systematic error of the data.Comment: 5 pages (Latex); 2 figures are included via epsfig; contribution to the workshop ``Future Physics at HERA'' at DESY, Hamburg, 1995/96; to be published in the proceedings; compressed postscript version also available at http://wwwcn.cern.ch/~graudenz/publications.htm

Two-Photon Annihilation into Baryon-Antibaryon Pairs

We study the handbag contribution to two-photon annihilation into baryon-antibaryon pairs at large energy and momentum transfer. We derive factorization of the process amplitude into a hard gamma gamma -> q qbar subprocess and form factors describing the soft q qbar -> B Bbar transition, assuming that the process is dominated by configurations where the (anti)quark approximately carries the full momentum of the (anti)baryon. The form factors represent moments of time-like generalized parton distributions, so-called B Bbar distribution amplitudes. A characteristic feature of the handbag mechanism is the absence of isospin-two components in the final state, which in combination with flavor symmetry provides relations among the form factors for the members of the lowest-lying baryon octet. Assuming dominance of the handbag contribution, we can describe current experimental data with form factors of plausible size, and predict the cross sections of presently unmeasured B Bbar channels.Comment: 20 pages latex, 4 figures. v2: minor clarifications, references update

The uniqueness of the invariant polarisation-tensor field for spin-1 particles in storage rings

We argue that the invariant tensor field introduced in [1] is unique under the condition that the invariant spin field is unique, and thereby complete that part of the discussion in that paper.Comment: 8 page