Measurement of deuteron spectra and elliptic flow in Pb\u2013Pb collisions at sqrt{s_{mathrm {NN}}} = 2.76 TeV at the LHC

Abstract

The transverse momentum (p_mathrm{T} ) spectra and elliptic flow coefficient (v_{2}) of deuterons and anti-deuterons at mid-rapidity (|y|<0.5) are measured with the ALICE detector at the LHC in Pb–Pb collisions at sqrt{s_{mathrm {NN}}} = 2.76 TeV. The measurement of the p_mathrm{T} spectra of (anti-)deuterons is done up to 8 GeV/c in 0–10% centrality class and up to 6 GeV/c in 10–20% and 20–40% centrality classes. The v_{2} is measured in the 0.8 < p_mathrm{T} <~5 GeV/c interval and in six different centrality intervals (0–5, 5–10, 10–20, 20–30, 30–40 and 40–50%) using the scalar product technique. Measured pi ^{pm }, K^{pm } and p+overline{mathrm {p}} transverse-momentum spectra and v_{2} are used to predict the deuteron p_mathrm{T} spectra and v_{2} within the Blast-Wave model. The predictions are able to reproduce the v_{2} coefficient in the measured p_mathrm{T} range and the transverse-momentum spectra for p_mathrm{T} > 1.8 GeV/c within the experimental uncertainties. The measurement of the coalescence parameter B_2 is performed, showing a p_mathrm{T} dependence in contrast with the simplest coalescence model, which fails to reproduce also the measured v_{2} coefficient. In addition, the coalescence parameter B_2 and the elliptic flow coefficient in the 20–40% centrality interval are compared with the AMPT model which is able, in its version without string melting, to reproduce the measured v_{2}(p_mathrm{T} ) and the B_2(p_mathrm{T} ) trend.