Projections of the three-dimensional $\pi^-$$\pi^+$ correlation function (points)and of the respective fits (lines) for seven $k_T$ intervals When projecting on one axis the other two components were required to be within (-0.03,0.03) GeV/$c$ The $k_T$ range is indicated on the right-hand side axis in GeV/$c$.

Pion HBT radii for the 5% most central Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76 $TeV, as function of $\langle$$k_T$$\rangle$ (red filled dots). The shaded bands represent the systematic errors. For comparison, parameters for Au--Au collisions at $\sqrt{s}$ =200 GeV are shown as blue open circles (The combined, statistical and systematic, errors on these measurements are below 4%.)The lines show model predictions (see text).

Pion HBT radii at $k_T$ = 0.3 GeV/$c$ for the 5% most central Pb-Pb at $\sqrt{s_{\rm NN}}=2.76 $TeV(red filled dot) and the radii obtained for central gold and lead collisions at lower energies at the AGS [35], SPS [36,37,38] and RHIC [39,40,41,42,30,43]. Model predictions are shown as lines.

Product of the three pion HBT radii at $k_T$ = 0.3 GeV/$c$ The ALICE result (red filled dot) is compared to those obtained for central gold and lead collisions at lower energies at the AGS [35], SPS [36,37,38] and RHIC [39,40,41,42,30,43].

The decoupling time extracted from $R_{\rm long}$($k_T$). The ALICE result (red filled dot) is compared to those obtained for central gold and lead collisions at lower energies at the AGS [35], SPS [36,37,38] and RHIC [39,40,41,42,30,43].