arXiv subjects

John Collins

Publications and source records attributed to John Collins.

41 records · Page 3Linked to original sources

arXiv2000

Subtraction method for NLO corrections in Monte-Carlo event generators for leptoproduction

In the case of the gluon-fusion process in deep-inelastic leptoproduction, I explicitly show how to incorporate NLO corrections in a Monte-Carlo event generator by a subtraction method. I calculate the parton densities to be used by the event generator in terms of MSbar densities. The method is generalizable. A particular motivation for treating the gluon-fusion process is to treat diffractive deep-inelastic scattering properly, since in diffractive scattering the gluon density dominates the quark densities. I also propose a modified algorithm for treating parton kinematics in event generators; the new algorithm results in much simpler formulae for the NLO corrections. A disadvantage of the new method is that some of the generated events may have negative weights. However, an adjustable cut-off function is present in the formalism, and this permits a renormalization-group-like transformation that can be used to at least reduce the proportion of events with negative weights.

hep-ph↗

arXiv1997

Light-cone Variables, Rapidity and All That

I give a pedagogical summary of the methods of light-cone variables, rapidity and pseudo-rapidity. Then I show how these methods are useful in analyzing diffractive high-energy collisions.

hep-ph↗

arXiv1995

Polarized Beam Jets

Handedness and a left-right asymmetry have been proposed as methods of probing the polarization of hard jets. If the analyzing powers for these observables are substantial they would provide useful tools for probing polarized hard scattering. This paper proposes that comparing these to the corresponding quantities in beam jets in polarized hadron-hadron collisions would be useful. These would shed light on the similarities and differences between the fragmentation of hard and soft jets. They would also suggest whether there is any useful possibility of measuring jet polarization. The left-right asymmetry of beam jets has already been measured and is large. But measurements of the handedness of beam jets have still to be done. They could be done in an upgraded HERMES detector at HERA.

hep-ph↗

arXiv1995

Measuring transverse spin correlations by 4-particle correlations in $e^+ e^-\to 2 \ {\rm jets}$

The azimuthal distribution of pairs of particles in a jet is sensitive to the transverse polarization of the quark initiating the jet, but with a sensitivity that involves a nonperturbative analyzing power. We show in detail how to measure the analyzing power from 4-hadron correlations in $e^+ e^- \to 2 \ {\rm jets}$. We explain the combinations of particle flavor that are likely to give the biggest effect.

hep-ph↗

arXiv1994

Measuring Parton Densities in the Pomeron

We present a program to measure the parton densities in the pomeron using diffractive deep inelastic scattering and diffractive photoproduction, and to test the resulting parton densities by applying them to other processes such as the diffractive production of jets in hadron-hadron collisions. Since QCD factorization has been predicted NOT to apply to hard diffractive scattering, this program of fitting and using parton densities might be expected to fail. Its success or failure will provide useful information on the space-time structure of the pomeron.

hep-ph↗