Higher-twist dynamics in large transverse momentum hadron production

A scaling law analysis of the world data on inclusive large-p(⊥) hadron production in hadronic collisions is carried out. Significant deviations from leading-twist perturbative QCD predictions at next-to-leading order are observed, particularly at high x(⊥)=2p(⊥)/sqrt[s]. In contrast, the production of prompt photons and jets exhibits near-conformal scaling behavior in agreement with leading-twist expectations. These results indicate a non-negligible contribution of higher-twist processes in large-p(⊥) hadron production, where the hadron is produced directly in the hard subprocess, rather than by quark and gluon fragmentation. Predictions for the scaling exponents at RHIC and LHC are given. Triggering on isolated large-p(⊥) hadron production will enhance the higher-twist processes. We also note that the use of isolated hadrons as a signal for new physics can be affected by the presence of direct hadron production.