The elliptic flow of muons from the decay of charm and bottom hadrons is measured in pp collisions at √s = 13 TeV using a data sample with an integrated luminosity of 150 pb-1 recorded by the ATLAS detector at the LHC. The muons from heavy-flavor decay are separated from light-hadron decay muons using momentum imbalance between the tracking and muon spectrometers. The heavy-flavor decay muons are further separated into those from charm decay and those from bottom decay using the distance-of closest-approach to the collision vertex. The measurement is performed for muons in the transverse momentum range 4-7 GeV and pseudorapidity range |η| < 2.4. A significant nonzero elliptic anisotropy coefficient θ2 is observed for muons from charm decays, while the θ2 value for muons from bottom decays is consistent with zero within uncertainties.

Aad, G., Abbott, B., Abbott, D.C., Abed Abud, A., Abeling, K., Abhayasinghe, D.K., et al. (2020). Measurement of azimuthal anisotropy of muons from charm and bottom hadrons in pp collisions at √s = 13 TeV with the ATLAS detector. PHYSICAL REVIEW LETTERS, 124(8), 082301 [10.1103/PhysRevLett.124.082301].

Measurement of azimuthal anisotropy of muons from charm and bottom hadrons in pp collisions at √s = 13 TeV with the ATLAS detector

Ceradini F.;D'Amico V.;Di Micco B.;Di Nardo R.;Martinelli L.;