(Left) The $\Xi^{\mp}\pi^{\pm}$ invariant mass distribution (Same-event pairs) in 1.8 $< \pt < 2.2$ GeV/$c$ and for the multiplicity class 20-40%. The background shape, using pairs from different events (Mixed-event background), is normalised to the counts in 1.49 $< M_{\Xi\pi} < $ 1.51 GeV/$c^2$ and 1.56 $< M_{\Xi\pi} < $ 1.58 GeV/$c^2$. (Right) The invariant mass distribution after subtraction of the mixed-event background The solid curve represents the combined fit, while the dashed line describes the residual background.