Direct- and resolved-photon threshold resummation for polarized high- pT hadron production at COMPASS

Abstract

We complete our earlier study of the "direct" part of the cross section and spin asymmetry for the photoproduction process γN → hX by analysing the "resolved" contribution, for which the photon couples like a hadron through its parton structure. The incident photon and nucleon are longitudinally polarized and one observes a hadron h at high transverse momentum pT . Soft or collinear gluon emissions generate large logarithmic threshold corrections which we resum to nextto-leading logarithmic order. We compare our results with recent spin asymmetry data by the COMPASS collaboration, highlighting the role of the fragmentation functions.

Power corrections in semi-inclusive deep inelastic scatterings at fixed target energies

“…However, the precise SIDIS data, recently published by COMPASS Collaboration [11], show almost one order of magnitude discrepancy between the data and the leading order (LO) theoretical prediction for the region where P h T ∼ Q and z h are large [17], and the next-to-leading order (NLO) corrections provide very little help to reduce this discrepancy [17,18]. Soft gluon resummation does help enhance the prediction of theoretical calculations for the high P h T region, but, not enough to make up the order of magnitude difference [19,20]. Although the P h T -integrated cross section, which is dominated by small-P h T regime, has been well described within the collinear factorization, a successful description of the full P h T -distribution is critically important for understanding QCD dynamics and extracting the multidimensional partonic structure of the nucleon.…”

Longitudinal spin structure of the nucleon at COMPASS

“…This hence demonstrates the applicability of the framework to our kinematical domain. The resummation technique has recently been extended to the polarised case [33] and applied to the COMPASS case. Results show improved agreement with polarised PDFs from DSSV++ [20], but the interpretation of the data is still affected by uncertainties arising from fragmentation functions.…”

Inclusive jet production as a probe of polarized parton distribution functions at a future EIC

“…Recently, a NLO computation of the double longitudinal spin asymmetry for inclusive jet production in polarized DIS has been performed in Ref. [13,14], using the narrow cone approximation [15] to enable a fully analytical calculation. Previous work has studied aspects of inclusive jet photoproduction in polarized collisions [16,17].…”