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 Δq(x) and the transverse spin distribution ΔTq(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 (6LiD) can be both longitudinally and transversely polarized with respect to the polarized 160 GeV/c µ+-beam. In transverse configuration ΔTq(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 ΔTq(x) is the measurement of two hadron production, introducing the chiral odd interference fragmentation function H1∢(z, Mh2). 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.