The \Dzt\ distributions in 0--30\% (full-red squares) \PbPb collisions, in pp (full-black circles), and in \pPb (empty-black circles) collisions from Ref.~ as a function of \zt. The boxes and vertical lines represent the systematic and statistical uncertainties, respectively The results are compared with an NLO pQCD \Dzt\ theory estimation (light brown-dashed band). Note the selection criteria for the \PbPb measurements and theory, and pp and \pPb collisions are different, as shown in the legend and discussed in the text.