Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudorapidity range and full azimuth in [Formula presented] and [Formula presented] collisions at [Formula presented]. The small-angle correlations observed in [Formula presented] collisions and at all centralities of [Formula presented] collisions are characteristic of hard-scattering processes previously observed in high-energy collisions. A strong back-to-back correlation exists for [Formula presented] and peripheral [Formula presented]. In c...
