Dresden 2013 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 27: Hadronenstruktur und -spektroskopie

HK 27.8: Vortrag

Dienstag, 5. März 2013, 16:00–16:15, HSZ-101

COMPASS results on transverse spin asymmetries in identified two-hadron production in SIDIS — •Christopher Braun — for the COMPASS collaboration — Uni Erlangen

The parton distribution function h₁ of a transversely polarized quark inside a transversely polarized nucleon, is chiral-odd and therefore not accessible in inclusive deep inelastic scattering. It can only be observed in semi-inclusive deep inelastic scattering (SIDIS) in combination with another chirally odd function like the two-hadron interference fragmentation function (IFF) H₁^◁. The 160 GeV/c polarized µ⁺ beam of CERN’s M2 beamline allows COMPASS to investigate the spin structure of the nucleon using polarized solid state targets.

In this contribution an overview of COMPASS results for the azimuthal asymmetries in two-hadron production is given. This includes the results on a polarized deuteron target from the data taken in the years 2002-04, as well as the first data set on a transversely polarized proton target taken in the year 2007 and a data set taken on the same target during 2010 to increase precision. An extraction of h₁ using the two-hadron IFF H₁^◁ has been carried out for the 2007 data. The COMPASS spectrometer allows an efficient particle identification, which can be used to determine the composition of the h⁺h⁻ pairs in terms of pions and kaons. The results for the possible combinations, optained very recently, will be discussed. In particular the asymmetries for π⁺π⁻ pairs will be compared to model predictions and the corresponding results from HERMES. − Supported by German BMBF