Beam energy and system dependence of rapidity-even dipolar flow

Abstract

New measurements of rapidity-even dipolar flow, veven1, are presented for several transverse momenta, pT, and centrality intervals in Au+Au collisions at [see formula in PDF] = 200, 39 and 19.6 GeV, U+U collisions at [see formula in PDF] = 193 GeV, and Cu+Au, Cu+Cu, d+Au and p+Au collisions at [see formula in PDF] = 200 GeV. The veven1 shows characteristic dependencies on pT, centrality, collision system and [see formula in PDF], consistent with the expectation from a hydrodynamic-like expansion to the dipolar fluctuation in the initial state. These measurements could serve as constraints to distinguish between different initialstate models, and aid a more reliable extraction of the specific viscosity η/s.