Benedikt Humpert

Multi-parton scattering and QCD radiation as sources of four-jet events

Abstract We compare the qualitative features for four-jet events arising from the QCD radiation process and from multi-parton scattering. The two processes are competitive at collider energies. We present experimental tests discriminating between the two reaction mechanisms.

Are there multiquark interactions

Abstract The simultaneous interaction of two (or more) pairs of quarks/gluons leads at collider energies to pair-wise p T - balanced four- (or more) jet events. We determine their cross section, which is at an appreciable level as compared to the two-jet cross section if the total transverse energy is not very large, and we analyze their kinematical characteristics. We expand on the implications and point to further possibilities for the search for such multiquark interactions.

ψψ production at collider energies

We estimate ψψ production at collider energies in the framework of perturbative QCD. TheO(αs2)−(αs4) parton cross-sections, with the non-relativistic approximation for the heavy quark bound states, are used. This first insight into the characteristics of the kinematical distributions allows predictions on the predominance of the quark, gluon orB meson production mechanisms in particular kinematical regions.

The production of gauge boson pairs by pp colliders

Abstract The simultaneous production of two gauge bosons from the set (W,Z,γ,γ∗) by p p colliders is considered. The dynamical characteristics of the lowest order two-parton contributions are analyzed. The four-parton background is small. The significance of Wγ (and also Z0γ) production in unravelling possible W, Z substructure is stressed.

Two Jet Production in

AbstractThe production of two quark/gluon jets in

Collisions

p\bar p

Two-jet production in p

collisions is analyzed. We determine the cross section dependence on the transverse momentum, the rapidities, and on the two-jet invariant mass, and we evaluate the sensitivity of the results on the theoretical input assumptions and the experimental cuts. We extrapolate these results into the TeV energy region.

\overline{p}

Abstract Using the parton model with leading-log QCD corrections, we extrapolate the cross section for p p 2-jet production into the multi-TeV energy region. We evaluate its dependence on the transverse momentum, the jet-jet invariant mass, and on the rapidities, and we expose the cross section sensitivity on the structure function parametrizations. Signatures for quark compositeness are given.