CGC/saturation approach for high energy soft interactions: ‘soft’ Pomeron structure and $$v_{n}$$vn in hadron and nucleus collisions from Bose–Einstein correlations

In the framework of our model of soft interactions at high energy based on the CGC/saturation approach, we show that Bose–Einstein correlations of identical gluons lead to large values of $$v_n$$vn. We demonstrate how three dimensional scales of high energy interactions, hadron radius, typical size of the wave function in diffractive production of small masses (size of the constituent quark), and the saturation momentum, influence the values of BE correlations, and in particular, the values of $$v_n$$vn. Our calculation shows that the structure of the ‘dressed’ Pomeron leads to values of $$v_n$$vn which are close to experimental values for proton–proton scattering, 20 % smaller than the observed values for proton–lead collisions and close to lead–lead collisions for 0–10 % centrality. Bearing this result in mind, we conclude that it is premature to consider that the appearance of long range rapidity azimuthal correlations are due only to the hydrodynamical behaviour of the quark–gluon plasma.