Nuclear Physics A Long-range angular correlations at the LHC with ALICE

The observation of long-range correlations on the near and away side —the double ridge — in high-multiplicity p–Pb collisions at sNN = 5.02 TeV and its similarity to Pb–Pb collisions remains one of the open questions from the p–Pb run at the Large Hadron Collider (LHC). It has been attributed to mechanisms that involve initial-state effects, such as gluon saturation and colour connections forming along the longitudinal direction, and final-state effects, such as parton-induced interactions and collective effects developing in a high-density system possibly formed in these collisions. In order to understand the nature of this double-ridge structure the two-particle correlation analysis has been extended to identified particles. The observed mass dependence in p-Pb resembles the pattern observed in Pb–Pb collisions and is compatible with expectations from hydrodynamics. The subtraction of the long-range structures allows the study of the hadron production belonging to the fragmentation of jets originating from low momentum-transfer scatterings (minijets)