Measurement of transversity signals in two hadron production at COMPASS

The quark structure of the nucleon at the twist two level can be completely described with three quark distribution functions: the spin averaged distribution function $q(x)$, the helicity distribution $\Delta q(x)$ and the transverse spin distribution $\Delta_{T}q(x)$. This last function, referred to as transversity, is chiral-odd and can only be measured in combination with another chiral-odd function. COMPASS is a fixed target experiment at the CERN SPS M2 beamline. Its target ($^{6}$LiD) can be both longitudinally and transversely polarized with respect to the polarized 160 GeV$/c \mu^{+}$ beam. In transverse configuration $\Delta_{T}q(x)$ can be measured in semi-inclusive deep-inelastic scattering (SIDIS), requiring the detection of hadronic products. A rather new probe of the transverse spin distribution function $\Delta_{T}q(x)$ is the measurement of two hadron production, introducing the chiral odd interference fragmentation function $H^{\sphericalangle}_{1}(z,M^{2}_{h})$. Results are presented for the years 2003-2004 including particle identification by using the information of the RICH detector. The analysis was performed using all positive/negative charged pairs and $z-$ordered pairs.