Gießen 2007 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 49: Poster
HK 49.2: Poster
Donnerstag, 15. März 2007, 16:00–17:00, P
Lambda polarization in transverse running at COMPASS — •Teresa Negrini, Rainer Joosten, and Jens Bisplinghoff — Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, Deutschland
COMPASS is a fixed target experiment on the SPS M2 beamline at CERN. Its target can be polarised both longitudinally and transversely with respect to the polarised 160 GeV/c µ+ beam. In 2002, 2003, and 2004, 20% of the beam-time was spent in the transverse configuration on a 6LiD target, allowing the measurement of transversity effects.
The measurement of the transverse spin quark distribution functions ΔTq(x) is an important part of the physics program of the COMPASS experiment. The transversity distributions, being chiral-odd objects, are not accessible in inclusive deep-inelastic scattering (DIS), requiring the presence of another chiral-odd object. At COMPASS, ΔTq(x) can be measured in semi-inclusive deep-inelastic scattering (SIDIS), where the fragmentation functions provide the other chiral-odd object.
The most promising channels for the measurement of the transversity distributions in semi-inclusive DIS are the Collins effect, the azimuthal asymmetries in two hadrons production and the spin transfer to the Lambda hyperons. In this contribution, we focus on the semi-inclusive Lambda production mechanism, showing the connection between the measured polarization and the ΔTq(x) functions. Preliminary results for the Lambda polarization as a function of the x Bjorken variable, based on the full COMPASS statistics with transverse spin target configuration, are presented. This work is supported by BMBF.