Related paper Charged-particle production as a function of the relative transverse activity classifier in pp, p$-$Pb, and Pb$-$Pb collisions at the LHC Schematic representation of the toward, transverse, and away regions in the azimuthal plane with respect to the leading particle, i.e.,the particle with the highest $p_{\rm T}$ in the event. Figure taken from Ref. . [png]