Threshold resummation for polarized high-pThadron production at COMPASS

Abstract

We study the cross section for the photoproduction process γN → hX where the incident photon and nucleon are longitudinally polarized and a hadron h is observed at high transverse momentum. Specifically, we address the "direct" part of the cross section, for which the photon interacts in a pointlike way. For this contribution we perform an all-order resummation of logarithmic threshold corrections generated by soft or collinear gluon emission to next-to-leading logarithmic accuracy. We present phenomenological results relevant for the COMPASS experiment and compare to recent COMPASS data.

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

“…This is also what we have previously achieved for the spin-averaged cross section [6] and in our study [15] of the direct part of the spin-dependent cross section. Here we extend the resummation to the polarized resolved part.…”

“…Here we perform the resummation at arbitrary fixed rapidity of the produced hadron, using the techniques developed in Refs. [6,15,[25][26][27].…”

“…[6] we have performed such a threshold resummation at next-to-leading logarithmic (NLL) accuracy for the spin-averaged cross section for γN → hX, finding that the resummed cross section shows a markedly better agreement with the experimental data than the fixed-order (next-to-leading order, NLO) one. In our recent paper [15] we have extended our calculations to the case of longitudinally polarized incoming photons and nucleons, considering first the direct part of the cross section for which the photon interacts in the usual point-like manner in the hard scattering. In the present paper we complete our study of the polarized case by also addressing the resolved-photon contributions where the photon reveals its partonic structure and interacts like a hadron.…”

“…In Section III we recall the threshold resummation formalism for (resolved) photoproduction. The relevant techniques are rather standard, and numerous details have been given in our previous papers [6,15], so we shall be brief here as well. Section IV presents phenomenological results for our theoretical predictions for the spin-dependent cross sections, as well as a comparison of our double-longitudinal spin asymmetries with COMPASS data.…”

Threshold and Jet Radius Joint Resummation for Single-Inclusive Jet Production

“…Instead, only fixedorder (FO) expansions of the threshold resummed cross section are currently available in the literature [15,22,23]. Note that these problems do not necessarily occur for observables with identified final state hadrons [24][25][26][27].…”