Transverse nucleon single-spin asymmetry for single-inclusive hadron and jet production at NLO accuracy

We investigate the single-spin asymmetry for the single-inclusive production of hadrons and jets in collisions of transversely polarized nucleons and unpolarized leptons, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mo>ℓ</a:mo> <a:msup> <a:mrow> <a:mi>N</a:mi> </a:mrow> <a:mrow> <a:mo stretchy="false">↑</a:mo> </a:mrow> </a:msup> <a:mo stretchy="false">→</a:mo> <a:mo stretchy="false">(</a:mo> <a:mi>h</a:mi> <a:mtext> </a:mtext> <a:mi>or</a:mi> <a:mtext> </a:mtext> <a:mtext>jet</a:mtext> <a:mo stretchy="false">)</a:mo> <a:mi>X</a:mi> </a:mrow> </a:math> . We compute the spin-dependent cross section within collinear twist-3 factorization in perturbative QCD at next-to-leading order (NLO) accuracy. In this approach, multiparton correlations generate a nonvanishing effect. For the present paper, we focus on correlations in the nucleon initial-state rather than in the fragmentation process. We explicitly verify that collinear twist-3 factorization is valid at the one-loop level. Our analytical results show that at NLO the relevant multiparton correlation functions in the nucleon are probed on their full support in momentum fractions. Our numerical analysis for collisions at the Electron-Ion Collider indicates that the NLO corrections can be large and are sensitive to the functional form of the twist-3 correlation functions.