Lawrence Berkeley National Laboratory

Dijet acoplanarity is dominated by vacuum (Sudakov) pQCD radiation even in Pb+Pb collisions, but future higher precision measurements of the tails of the acoplanarity distributions can help to resolve separately the medium opacity, χ=L/λ and the color screening scale μ2 from the path averaged BDMS saturation scale Qs2[χ,μ]=∫dLqˆ(E,T(L))∝μ2L/λ that is already well constrained by nuclear modification factor data on RAA(pT). We compare Gaussian (BDMS) and non-Gaussian (GLV) models of medium broadening of vacuum (Sudakov) induced acoplanarity distributions in A+A. With few percent accuracy on the ratio of A+A to p+p distributions, experiments can easily identify non-Gaussian Landau and Rutherford tails due to multiple collisions. However, we find that sub-percent precision will be required to constrain χ and μ separately from Qs.