Direct photon elliptic flow in Pb–Pb collisions at sNN=2.76 TeV

Publication date: Available online 23 November 2018Source: Physics Letters BAuthor(s): S. Acharya, F.T. -. Acosta, D. Adamová, J. Adolfsson, M.M. Aggarwal, G. Aglieri Rinella, M. Agnello, N. Agrawal, Z. Ahammed, S.U. Ahn, S. Aiola, A. Akindinov, M. Al-Turany, S.N. Alam, D.S.D. Albuquerque, D. Aleksandrov, B. Alessandro, R. Alfaro Molina, Y. Ali, A. AliciAbstractThe elliptic flow of inclusive and direct photons was measured at mid-rapidity in two centrality classes 0–20% and 20–40% in Pb–Pb collisions at sNN=2.76 TeV by ALICE. Photons were detected with the highly segmented electromagnetic calorimeter PHOS and via conversions in the detector material with the e+e− pairs reconstructed in the central tracking system. The results of the two methods were combined and the direct-photon elliptic flow was extracted in the transverse momentum range 0.9<pT<6.2GeV/c. A comparison to RHIC data shows a similar magnitude of the measured direct-photon elliptic flow. Hydrodynamic and transport model calculations are systematically lower than the data, but are found to be compatible.

Source: Physics Letters B - November 24, 2018 Category: Physics Source Type: research