Azimuthal correlations from transverse momentum conservation and possible local parity violation

We analytically calculate the contribution of transverse momentum conservation to the azimuthal correlations that have been proposed as signals for possible local strong parity violation and recently have been measured in heavy ion collisions. These corrections are on the order of the inverse of the total final-state particle multiplicity and, thus, are on the same order as the observed signal. The corrections contribute with the same sign to both like-sign and opposite-sign pair correlations. Their dependence on the momentum is in qualitative agreement with the measurements by the solenoidal tracker at the BNL Relativistic Heavy Ion Collider Collaboration, while the pseudorapidity dependence differs from the data.