Spin densities in the transverse plane and generalized transversity distributions
Deutsches Elektronen-Synchroton DESY, 22603, Hamburg, Germany
2 Department of Physics and Astronomy, Vrije Universiteit, De Boelelaan 1081, 1081, HV Amsterdam, The Netherlands
We show how generalized quark distributions in the nucleon describe the density of polarized quarks in the impact parameter plane, both for longitudinal and transverse polarization of the quark and the nucleon. This density representation entails positivity bounds including chiral-odd distributions, which tighten the known bounds in the chiral-even sector. Using the quark equations of motion, we derive relations between the moments of chiral-odd generalized parton distributions of twist two and twist three. We exhibit the analogy between polarized quark distributions in impact parameter space and transverse momentum dependent distribution functions.
© Springer-Verlag, 2005