Higher-twist term in inclusive pion production at large transverse momentum

Abstract

We calculate the absolute rate and kinematic dependence of the cross sections for the high-twist subprocesses $\mathrm{qG}\ensuremath{\rightarrow}\ensuremath{\pi}q$ and $q\overline{q}\ensuremath{\rightarrow}\ensuremath{\pi}G$ in perturbative quantum chromodynamics (QCD). These cross sections are used to estimate the high-twist contribution to large-transverse-momentum inclusive single-pion production in hadronic collisions. We compare the normalization of these terms with leading-order minimum-twist QCD processes such as $\mathrm{qG}\ensuremath{\rightarrow}\mathrm{qG}$. The high-twist contributions are shown to be quantitatively important for ${p}_{T}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{l}6$ ${\mathrm{GeV}}^{2}$ and ${x}_{T}\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{g}0.5$, and they should be included in detailed analyses of data. We discuss cross sections and charge ratios, and we comment briefly about inclusive spin-correlation measurements at large ${p}_{T}$.