Azimuthal Anisotropy of Heavy-Flavor Decay Electrons in $p$-Pb Collisions at $ \sqrt{s_{\rm NN}}$ = 5.02 TeV

Angular correlations between heavy-flavour decay electrons and charged particles at mid-rapidity (|$\eta$| < 0.8) are measured in p-Pb collisions at $\sqrt{s_{NN}}$ = 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 < $p_{T}$ < 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.