Quantum-chromodynamic approach for the large-transverse-momentum production of particles and jets

Abstract

It is shown that if, in a calculation of high-transverse-momentum ($p_{\perp }$) meson production in hadron-hadron collisions, one includes not only the scale-breaking effects that might be expected from asymptotically free theories but also the effects due to the transverse momentum of quarks in hadrons and further adds contributions from quark-gluon and gluon-gluon scattering to those of quark-quark scattering then the results are not inconsistent with the data. The approach yields the correct magnitude and an apparent approximate $\frac{1}{p_{\perp }^8}$ behavior in accord with single-particle data for the energy range currently observed. Two-particle correlations are examined. Because of scale-breaking effects and the presence of gluons, the theory does not have the problem of predicting too many away-side hadrons at large $p_{\perp }$ as did an earlier quark-quark scattering "black-box" approach. We conclude that the quantum-chromodynamics approach is in reasonable accord with the data although theoretical uncertainties (especially at low $p_{\perp }$) make incontrovertible conclusions impossible at present. Crucial tests of the theory require higher $p_{\perp }$ than are now available; estimates for this region are made.