Transverse spin effects in SIDIS at 6 GeV with transversely polarized target using the CLAS Detector

Aula Edificio 22 (Laboratori Nazionali di Frascati)

Aula Edificio 22

Laboratori Nazionali di Frascati

Harut Avagyan (Jefferson Lab)
In the recent years it became clear that understanding of the orbital motion and in particular the role of partonic initial and final state interactions of quarks is crucial in construction of a more complete picture of the nucleon in terms of elementary quarks and gluons. To this end Transverse Momentum Dependent (TMDs) parton distributions functions are under intense investigation both from the experimental and theoretical side. Great progress has been made since then in measurements of different Single Spin Asymmetries (SSAs) in semi-inclusive processes providing access to TMDs In this talk a study of spin azimuthal asymmetries in semi-inclusive DIS using 6 GeV polarized electron beam, a transversely polarized HD-Ice target and the CEBAF Large Angle Spectrometer (CLAS) will be presented. Transverse target single-spin asymmetries (TTSA) and transverse spin-dependent double-spin asymmetries (TDSA) will be measured via semi-inclusive pion production in the e-p interaction, in the region of hard-scattering kinematics. The protons will be transversely polarized while the electrons will carry a longitudinal polarization. The x, z and pT dependencies of the TTSA will be studied over a wide range of kinematics. They will provide an access to the Sivers function (leading twist), describing the transverse motion of the quarks in a transversely polarized nucleon, the transversity function describing the transverse polarization of quarks in a transversely polarized nucleon, and the “pretzelosity” describing the transverse momentum distribution of transversely polarized quarks in a transversely polarized nucleon. This is the first low energy (high x) measurement from a transversely polarized target, which will substantially improve the statistical uncertainties of HERMES on the proton and bridge to the low x COMPASS results on the deuteron and (in the future) on the proton.
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