The invariant mass distribution of $\Lambda\pi^{+} + \overline{\Lambda}\pi^{-}$ pairs (a) and the charge conjugates (c) in $|y|<0.5$ produced in pp collisions at $\sqrt{s} = 13$ TeV for $1.8 < p_{\rm T,\Lambda\pi} < 2.0$ GeV/$c$ and the I+II+III multiplicity class (full black circles). The combinatorial background estimated with the event mixing technique is shown as open red squares in the (a) and (c) panels, whereas the invariant mass distributions after combinatorial background subtraction are shown in the (b) and (d) panels together with the fits to the signal and the residual background contributions. The solid red curves are the results of the combined fit and the dashed black lines represent the residual background.