Perturbative QCD and beyond: azimuthal angle correlations in deuteron-deuteron scattering from Bose-Einstein correlations

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In this paper, we found within the framework of perturbative QCD, that in deuteron-deuteron scattering the Bose-Einstein correlations due to two parton showers production, induce azimuthal angle correlations, with three correlation lengths: the size of the deuteron (RD), the proton radius (Rₙ), and the size of the BFKL Pomeron which, is closely related to the saturation momentum (Rc 1/Qₛ). These correlations are independent of the values of rapidities of the produced gluons (long range rapidity correlations), for large rapidities (|y₁ - y₂| ≥ 1), and have no symmetry with respect to ϕ→ π- ϕ (pₜ₁ → - pₜ₁). Therefore, they give rise to vₙ for all values of n, not only even values. The contributions with the correlation length RD and Rₙ crucially depend on the non-perturbative contributions, and to obtain estimates of their values, requiries a lot of modeling, while the correlations with Rc 1/Qₛ have a perturbative QCD origin, and can be estimated in the ColorGlass Condensate (CGC) approach.