Berlin 2005 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 30: Elektromagnetische und Hadronische Proben
HK 30.4: Vortrag
Dienstag, 8. März 2005, 17:30–17:45, TU MA001
Tranversity signals in two pion correlation at COMPASS — •Rainer Joosten — Helmholtz Institut für Strahlen- und Kernphysik,Rheinische Friedrich-Wilhelms-Universität Bonn
The cross-section for deep inelastic scattering off spin 1/2 hadrons can be parametrised in leading order in terms of three quark distribution functions: the helicity averaged distribution q(x), the longitudinal helicity distribution Δq(x) and the transverse spin distribution ΔTq(x). This last distribution function, referred to as transversity, is chiral-odd and can only be measured in combination with a chiral-odd function. So far, attempts were made to measure ΔTq(x) in combination with the Collins fragmentation-function H1⊥(z), requiring the partial detection of the hadronic products (semi-inclusive measurement). Another probe is the measurement of two hadron production introducing the chiral odd interference fragmentation function H1< −0.3 em )(z). An asymmetry is expected in the azimuthal angle of the hadron plane which should depend on ϕR+ϕS, where ϕS is the angle of the initial quark spin and ϕR the angle of the hadron plane in the lepton scattering plane. Some models even expect an interference term in the region of the ρ-mass. COMPASS is a fixed target experiment on the SPS M2 beamline at CERN. Its 6LiD target can be polarised both longitudinally and transversally with respect to the polarised 160 GeV/c µ+ beam. 20% of the beam-time is spent in the transverse configuration, allowing the measurement of transversity effects. First results of the analysis of two hadron production will be reported. This work is supported by the BMBF.