First extraction of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">Λ</mml:mi></mml:math> polarizing fragmentation function from Belle <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math> data
U. D’Alesio, F. Murgia, Marco Zaccheddu
Abstract
We present a thorough phenomenological analysis of the experimental data from Belle Collaboration for the transverse $\mathrm{\ensuremath{\Lambda}}$ and $\overline{\mathrm{\ensuremath{\Lambda}}}$ polarization, measured in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation processes, for the case of associated (with a light charged hadron) and inclusive (plus a jet) production. Within a transverse momentum dependent (TMD) approach we show how this intriguing phenomenon can be accounted for. This allows for the first ever extraction of the quark polarizing fragmentation function for a $\mathrm{\ensuremath{\Lambda}}$ hyperon, a TMD distribution giving the probability that an unpolarized quark fragments into a transversely polarized spin-$1/2$ hadron.