Polarized heavy quark photoproduction in next to leading order

Abstract

Results of our next-to-leading order analytic calculation for longitudinally polarized photoproduction of heavy quarks are presented. Certain differential cross sections and the corresponding asymmetries are computed for energy ranges accessible to CERN and HERA. We argue that determination of the polarized gluon distribution is possible at both places: at HERA certain acceptance cuts are necessary.Deep Inelastic Scattering (DIS) of longitudinally polarized particles has been very useful in extracting the polarized valence distributions. However, it is quite limited in extracting the polarized gluon distribution Ag. Much was already said at this Workshop about the importance of knowing Ag, and there is no need to talk about it any further. In order to extract Ag with a good accuracy one needs experiments involving longitudinally polarized reactions dominated by subprocesses with initial gluons.One such reaction is the inclusive polarized photoproduction of heavy quarks:which at leading order (LO) proceeds through the subprocess:There are several experimental proposals on the subject in various stages of approval [1]. Next-to-leading order corrections (NLOC) are very important for several reasons: a) The leading order estimates depend strongly on the a priory unknown renormalization and factorization scales; in general the NLOC reduce this uncertainty. More precisely, going to one level higher in the strong coupling c~ may reduce the uncertainty by order a~; b) NLOC may be large and negative in some regions of phase space, making cross sections small and difficult to measure; c) At NLO, subprocesses unrelated to the LO ones could come into play. In principle, the contribution of such subprocesses could be significant in certain important parts of *) Present address:

Inclusive D production in $\gamma \gamma$ collisions: including the single-resolved contribution with massive quarks

“…In the course of our work we found several misprints in Ref [10]. which are not mentioned in detail here, but can be found in[16].…”

“…[10,16] and B.A. Kniehl and M. Spira for providing us with programs for the calculation of the doubleresolved contributions.…”

“…We thank Z. Merebashvili for clarifying communications about Refs. [10,16] and B.A. Kniehl and M. Spira for providing us with programs for the calculation of the doubleresolved contributions.…”

Polarized photoproduction of heavy quarks in next-to-leading order

“…The integrals listed in the Appendices A and C of [9] have been very useful. Some remaining integrals are given in an Appendix of [10].…”

“…Subsequently we present results for Q =c-quark with m = 1.5 GeV only at S γp = √ S = 10 GeV, relevant to the experiments (a) and (b) of [1]. Higher energies and Q =bquark are considered elsewhere [10]. Also, in relation with (4a), we take µ R = µ.…”