arXiv subjects

Daniel Boer

Publications and source records attributed to Daniel Boer.

76 records · Page 5Linked to original sources

arXiv1999

Color gauge invariance in the Drell-Yan process

We consider the color gauge invariance of a factorized description of the Drell-Yan process cross section. In particular, we focus on the next-to-leading twist contributions for polarized scattering and on the cross section differential in the transverse momentum of the lepton pair in the region where the transverse momentum is small compared to the hard scale. The hadron tensor is expressed in terms of manifestly color gauge invariant, nonlocal operator matrix elements and a color gauge invariant treatment of soft gluon poles is given. Also, we clarify the discrepancy between two published results for a single spin asymmetry in the Drell-Yan cross section. This asymmetry arises if such a soft gluon pole is present in a specific twist-three hadronic matrix element.

hep-ph↗

arXiv1999

Angular dependences in electroweak semi-inclusive leptoproduction

We present the leading order unpolarized and polarized cross sections in electroweak semi-inclusive deep inelastic leptoproduction. The azimuthal dependences in the cross section differential in the transverse momentum of the vector boson arise due to intrinsic transverse momenta of the quarks. However, the presented asymmetries are not suppressed by inverse powers of the hard scale. We discuss the different opportunities to measure specific asymmetries as offered by neutral compared to charged current processes and point out the optimal kinematical regions. The present and (proposed) future HERA collider experiments would be most suitable for measuring some of the asymmetries discussed here, especially in case of Lambda production.

hep-ph↗

arXiv1999

Intrinsic transverse momentum and transverse spin asymmetries

We investigate leading twist transverse momentum dependent origins of transverse spin asymmetries in hadron-hadron collisions. The chiral-odd T-odd distribution function with intrinsic transverse momentum dependence, which would signal an intrinsic handedness of quarks inside a hadron, could account for single spin asymmetries and at the same time for the large cos(2 phi) asymmetry in the unpolarized Drell-Yan cross section, which still lacks understanding. We show explicitly how it would relate unpolarized and polarized observables measurable with proton-proton collisions at RHIC. It would offer a new possibility to access the transversity distribution function.

hep-ph↗

arXiv1999

Investigating the origins of transverse spin asymmetries at RHIC

We discuss possible origins of transverse spin asymmetries in hadron-hadron collisions and propose an explanation in terms of a chiral-odd T-odd distribution function with intrinsic transverse momentum dependence, which would signal a correlation between the transverse spin and the transverse momentum of quarks inside an unpolarized hadron. We will argue that despite its conceptual problems, it can account for single spin asymmetries, for example in p + p(transversely polarized) -> pion + X, and at the same time for the large cos(2 phi) asymmetry in the unpolarized Drell-Yan cross section, which still lacks understanding. We use the latter asymmetry to arrive at a crude model for this function and show explicitly how it relates unpolarized and polarized observables in the Drell-Yan process, as could be measured with the proton-proton collisions at RHIC. Moreover, it would provide an alternative method of accessing the transversity distribution function h_1. For future reference we also list the complete set of azimuthal asymmetries in the unpolarized and polarized Drell-Yan process at leading order involving T-odd distribution functions with intrinsic transverse momentum dependence.

hep-ph↗