Evidence of medium response to hard probes using correlations of Z bosons with hadrons in heavy ion collisions

The first measurement of pseudorapidity and azimuthal angle distributions relative to the momentum vector of a Z boson for low transverse momentum ( p T) charged hadrons in lead-lead (PbPb) collisions is presented. By studying the hadrons produced in an event with a high- p T Z boson ( 40p T. A significant modification of the distributions for charged hadrons in the range 1