Narrow Results

The valence transversity distributions of the u- and the d-quarks have been extracted point-by-point from single-hadron production and dihadron production data measured in semi-inclusive deep inelastic scattering and in e⁺e annihilation. The extraction is based on some simple assumptions and does not require any parametrization. The transversity distributions are found to be compatible with each other and with previous analyses.

The COMPASS measurements of the azimuthal asymmetries in the hadron pairs production in DIS on transversely polarised targets are here presented. Results on oppositely charged pion and kaon pairs produced on both deuteron and proton targets are shown. They have been used to update the calculation of the Transversity function which was previously extracted from the asymmetries measured from un-identified hadron pairs. Also a new method for the direct measurement of the integral of Transversity using both COMPASS and BELLE results is presented.

The valence transversity distributions of the u- and the d-quarks have been extracted point-by-point from single-hadron production and dihadron production data measured in semi-inclusive deep inelastic scattering and in $e^{+}{e}^{}$ annihilation. The transversity distributions are found to be compatible with each other and with previous analyses.

In the fragmentation of a transversely polarized quark a left-right asymmetry, the Collins asymmetry, is expected for each hadron produced in the process $\mu N\to {\mu }^{\prime }{h}^{+}{h}^{-}X$. Similarly, an asymmetry is also expected for the hadron pair, the dihadron asymmetry. Both asymmetries have been measured to be different from zero on transversely polarised proton targets and have allowed for first extractions of the transversity distributions. From the high statistics COMPASS data we have further investigated these asymmetries getting strong indications that the two mechanisms are driven by a common physical process.