Charge asymmetry dependence of anisotropic flow in pPb and PbPb collisions with the CMS experiment

In nucleus-nucleus collisions, the linear dependence found for the elliptic flow harmonic of both positive or negative charged particles as a function of event charge asymmetry is predicted by the phenomenon known as the Chiral Magnetic Wave (CMW) due to its induced electric quadrupole moment. Here, the event charge asymmetry A ch is defined as N+−N−N++N− , where N + and N − are the number of positive and negative charged particles, respectively. However, other scenarios are also possible and may provide alternative explanations for the experimental results. New measurements of elliptic ( v 2 ) and triangular ( v 3 ) flow for positive and negative charged particles as a function of A ch in pPb and PbPb collisions at sNN=5.02 TeV are presented, using data collected by the CMS experiment during the LHC runs 1 and 2. The slopes and intercepts of the charged-dependent v n harmonics vs. A ch are directly compared for pPb and PbPb collisions with similar charged-particle multiplicities, where a strong CMW effect is not expected in very high multiplicity pPb events. Moreover, a comparison is made of the slope parameters between v 2 and v 3 harmonics normalized by the inclusive charge particle v n in PbPb collisions as a function of centrality. These results provide a means to discriminate between the CMW and other scenarios such as local charge conservation as possible explanations for the observed charge dependent behavior.