First extraction of the $Lambda$ polarising fragmentation function from Belle $e^+e^-$ data

We present a thorough phenomenological analysis of the experimental data from Belle Collaboration for the transverse $Lambda$ and $barLambda$ polarisation, measured in $e^+e^-$ annihilation processes, for the case of inclusive (plus a jet) and associated production with a light charged hadron. This allows for the first ever extraction of the quark polarising fragmentation function for a $Lambda$ hyperon, a transverse momentum dependent distribution giving the probability that an unpolarised quark fragments into a transversely polarised spin-1/2 hadron.