Bose enhancement and the ridge

Abstract

We point out that Bose enhancement in a hadronic wave function generically leads to correlations between produced particles. We show explicitly, by calculating the projectile density matrix in the Color Glass Condensate approach to high-energy hadronic collisions, that the Bose enhancement of gluons in the projectile leads to azimuthal collimation of long range rapidity correlations of the produced particles, the so-called ridge correlations.

Comments: 5 pages, 1 figure; v2: 6 pages, 1 figure, discussions enlarged and technical details added, figure changed, final version