On correlations in high-energy hadronic processes and the CMS ridge: A manifestation of quantum entanglement?

Abstract

We discuss the possibility of quantum entanglement for pairs of charged particles produced in high-energy $pp$-collisions at the LHC. Using a framework of interacting Wilson lines, we calculate 2-D and 1-D two-particle angular correlation functions in terms of the differences of the pseudorapidities and azimuthal angles of the produced particles. The calculated near-side angular correlation shows a localized maximum around $\Delta\phi \approx 0$, though it is less pronounced compared to the peak observed by the CMS Collaboration. We argue that this soft correlation is universal and insensitive to the specific properties of the matter (quark-gluon plasma, QCD vacuum, etc.) used to describe hadronic states---though such properties can be included to further improve the results.