We calculate the radiative parton energy loss in the deeply inelastic scattering (DIS) off a large nucleus within a generalized high-twist approach. The final gluon radiation spectrum is a convolution of the hard partonic part and the transverse momentum dependent (TMD) quark-gluon correlation function, without the twist expansion in the transverse momentum of the initial gluons used in original high twist approach. The TMD quark-gluon correlation function can be factorized approximately as the product of initial quark distribution and TMD gluon distribution which can be used to define the generalized or TMD jet transport coefficient. The radiation spectrum will recover the Gylassy-Levai-Vitev (GLV) result in the first order of the opacity expansion, under the static scattering center and soft gluon radiation approximation. We also investigate numerically the difference as a result of the soft gluon radiation approximation, under the static scattering center approximation.

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.

Using the CUJET3=DGLV+VISHNU jet-medium interaction framework, we show that dijet azimuthal acoplanarity in high energy A + A collisions is sensitive to possible non-perturbative enhancement of the jet transport coefficient, qˆ(T,E), in the QCD crossover temperature T ∼ 150–300 MeV range. With jet-medium couplings constrained by global RHIC& LHC χ2 fits to nuclear modification data on RAA(pT > 20) GeV, we compare predictions of the medium induced dijet transverse momentum squared, Qs2∼〈qˆL〉∼Δϕ2E2, in two models of the temperature, T, and jet energy E dependence of the jet medium transport coefficient, qˆ(T,E)). In one model, wQGP, the chromo degrees of freedom (dof) are approximated by a perturbative dielectric gas of quark and gluons dof. In the second model, sQGMP, we consider a nonperturbative partially confined semi-Quark-Gluon-Monopole-Plasma with emergent color magnetic dof constrained by lattice QCD data. Unlike the slow variation of the scaled jet transport coefficient, qˆwQGP/T3, the sQGMP model qˆsQGMP/T3 features a sharp maximum in the QCD confinement crossover T range. We show that the dijet path averaged medium induced azimuthal acoplanarity, Δϕ2, in sQGMP is robustly ∼ 2 times larger than in perturbative wQGP. even though the radiative energy loss in both models is very similar as needed to fit the same RAA data. Future A+A dijet acoplanarity measurements constrained together with single jet RAA and νn measurements therefore appears to be a promising strategy to search for possible signatures of critical opalescence like phenomena in the QCD confinement temperature range.