Measurement of non-prompt ${\text{D}}^{0}$ -meson elliptic flow in Pb–Pb collisions at $\sqrt{{s}_{\text{NN}}}=5.02$ TeV

The elliptic flow $\left({v}_{2}\right)$ of ${\text{D}}^{0}$ mesons from beauty-hadron decays (non-prompt ${\text{D}}^{0}\right)$ was measured in midcentral (30–50%) Pb–Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{{s}_{\text{NN}}}=5.02$ TeV with the ALICE detector at the LHC. The ${\text{D}}^{0}$ mesons were reconstructed at midrapidity $\left(|y|<0.8\right)$ from their hadronic decay ${D}^{0}\to {K}^{-}{\pi }^{+}$ , in the transverse momentum interval $2<{p}_{\text{T}}<12$ GeV/c. The result indicates a positive ${v}_{2}$ for non-prompt ${\text{D}}^{0}$ mesons with a significance of 2.7 $\sigma $ . The non-prompt ${\text{D}}^{0}$ -meson ${v}_{2}$ is lower than that of prompt non-strange D mesons with 3.2 $\sigma $ significance in $2<{p}_{\text{T}}<8\phantom{\rule{3.33333pt}{0ex}}\text{GeV}/c$ , and compatible with the ${v}_{2}$ of beauty-decay electrons. Theoretical calculations of beauty-quark transport in a hydrodynamically expanding medium describe the measurement within uncertainties.