Azimuthal anisotropy of heavy-flavour decay electrons in p-Pb collisions at $ \sqrt{s_{\rm NN}}$ = 5.02 TeV

TL;DR

This study measures azimuthal anisotropy of heavy-flavour decay electrons in p-Pb collisions at 5.02 TeV, revealing a significant elliptic flow component in high-multiplicity events, indicating collective behavior.

Contribution

It presents the first measurement of heavy-flavour decay electron azimuthal anisotropy in small collision systems, highlighting collective effects in p-Pb collisions.

Findings

Positive v2 coefficient for heavy-flavour electrons in high-multiplicity events

Jet contributions can be effectively subtracted using low-multiplicity data

Results suggest collective behavior similar to light-flavour hadrons

Abstract

Angular correlations between heavy-flavour decay electrons and charged particles at mid-rapidity ($|\eta| < 0.8$) are measured in p-Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV. The analysis is carried out for the 0-20% (high) and 60-100% (low) multiplicity ranges. The jet contribution in the correlation distribution from high-multiplicity events is removed by subtracting the distribution from low-multiplicity events. An azimuthal modulation remains after removing the jet contribution, similar to previous observations in two-particle angular correlation measurements for light-flavour hadrons. A Fourier decomposition of the modulation results in a positive second-order coefficient ($v_{2}$) for heavy-flavour decay electrons in the transverse momentum interval $1.5 < p_{\rm{T}} < 4$ GeV/$c$ in high-multiplicity events, with a significance larger than $5\sigma$. The results are compared with those of charged particles at mid-rapidity and of inclusive muons at forward rapidity. The $v_2$ measurement of open heavy-flavour particles at mid-rapidity in small collision systems could provide crucial information to help interpret the anisotropies observed in such systems.