Negative elliptic flow from anomaly induced DCC formation Original Research Article

We discuss characteristic experimental signatures related to the mechanism of DCC formation triggered by the chiral U(1) anomaly in relativistic heavy ion collisions. We predict an enhancement of the fraction of neutral pions compared with all pions in the direction perpendicular to the scattering plane. To quantify the effect on the angular distribution of neutral pions, we compute the elliptic flow parameter v2 as a function of the transverse momentum. We find values of order −0.05 at small momenta for neutral pions. We also compute the v2 parameter for inclusive photons, which is easier to measure, and confirmed that the negative a few percent effect prevails in this observable.