Elliptic flow of muons from heavy-flavour hadron decays at forward rapidity in Pb-Pb collisions at √s_NN = 2.76 TeV

The elliptic flow, v₂ , of muons from heavy-flavour hadron decays at forward rapidity ( 2.5 < y < 4 ) is measured in Pb–Pb collisions at √s_NN = 2.76 TeV with the ALICE detector at the LHC. The scalar product, two- and four-particle Q cumulants and Lee–Yang zeros methods are used. The dependence of the v₂ of muons from heavy-flavour hadron decays on the collision centrality, in the range 0–40%, and on transverse momentum, p_T , is studied in the interval 3 < p_T < 10   GeV/c . A positive v₂ is observed with the scalar product and two-particle Q cumulants in semi-central collisions (10–20% and 20–40% centrality classes) for the p_T interval from 3 to about 5   GeV/c with a significance larger than 3σ, based on the combination of statistical and systematic uncertainties. The v₂ magnitude tends to decrease towards more central collisions and with increasing p_T . It becomes compatible with zero in the interval 6 < p_T < 10   GeV/c . The results are compared to models describing the interaction of heavy quarks and open heavy-flavour hadrons with the high-density medium formed in high-energy heavy-ion collisions.