CGC/saturation approach for high energy soft interactions:   $\mathbf{v_2}$ in proton-proton collisions
  In this paper we continue our program to construct a model for high energy soft interactions, based on the CGC/saturation approach. We demonstrate that in our model which describes diffractive physics as well as multi-particle production at high energy, the density variation mechanism leads to the value of $v_2$ which is about $60\% \div 70\%$ of the measured $v_2$. Bearing in mind that in CGC/saturation approach there are two other mechanisms present: Bose enhancement in the wave function and local anisotropy, we believe that the azimuthal long range rapidity correlations in proton-proton collisions stem from the CGC/saturation physics, and not from quark-gluon plasma production. 
E. Gotsman (Tel Aviv U.), E. Levin (Tel Aviv U./UTFSM), U. Maor (Tel   Aviv U.) and S.Tapia (UTFSM)
hep-ph