Measurement of azimuthal anisotropy of muons from charm and bottom hadrons in $pp$ collisions at $\sqrt{s}=13$ TeV with the ATLAS detector

TL;DR

This paper measures the azimuthal anisotropy of muons from charm and bottom hadron decays in proton-proton collisions at 13 TeV, revealing a significant elliptic flow for charm but not for bottom muons, using ATLAS data.

Contribution

It provides the first measurement of heavy-flavor muon elliptic flow in $pp$ collisions at 13 TeV, distinguishing charm and bottom contributions with novel separation techniques.

Findings

Significant non-zero $v_{2}$ for charm decay muons.

$v_{2}$ for bottom decay muons is consistent with zero.

Demonstrates heavy-flavor flow differences in $pp$ collisions.

Abstract

The elliptic flow of muons from the decay of charm and bottom hadrons is measured in $pp$ collisions at $\sqrt{s}=13$ 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 $|\eta|<2.4$. A significant non-zero elliptic anisotropy coefficient $v_{2}$ is observed for muons from charm decays, while the $v_{2}$ value for muons from bottom decays is consistent with zero within uncertainties.