Title: Investigation of particle anti-particle elliptic flow difference.

The azimuthal anisotropy of particle emission in the transverse plane, known as  anisotropic flow, is used to study the properties of strongly interacting hot and dense medium created in heavy-ion collision. Anisotropic flow coefficients are the key observables which reflect the viscous hydrodynamic response to the initial spatial anisotropy, produced in the early stages of the collision. In previous studies [1] performed by the STAR collaboration at the Relativistic Heavy Ion Collider (RHIC) the increase of the elliptic flow (v2) difference between particles and antiparticles at the lower collision energies has been observed.

In this talk, we will present the STAR measurement of the two- and four-particle flow correlations for identified particles as a function of centrality, transverse momentum and beam energy. Our measurements will be compared with the EPOS model simulations as well, that will help in better understanding the sources of the proton-antiproton elliptic flow difference.

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[1] STAR Collaboration: Phys. Rev. C 88 (2013) 14902