Can the total angular momentum of u-quarks in the nucleon be accessed at HERMES?

F. Ellinghaus; W.-D. Nowak; A.V. Vinnikov; Z. Ye

doi:10.1140/epjc/s2006-02529-3

EPJ

Can the total angular momentum of u-quarks in the nucleon be accessed at HERMES?

F. Ellinghaus¹, W.-D. Nowak², A.V. Vinnikov²^,3^* and Z. Ye⁴

¹ Department of Physics, University of Colorado, Boulder, Colorado, 80309-0390, USA
² DESY, 15738, Zeuthen, Germany
³ BLTP JINR, 141980, Dubna, Moscow region, Russia
⁴ DESY, 22603, Hamburg, Germany

Received: 2 September 2005
Revised: 17 February 2006
Published online: 31 March 2006

Abstract

We investigate the possibility of acquiring information on the generalized parton distribution E and, through a model for E, also on the u-quark total angular momentum J_u by studying deeply virtual Compton scattering and hard exclusive ρ⁰ electroproduction on a transversely polarized hydrogen target at HERMES. It is found that a change in J_u from zero to 0.4 corresponds to a 4σ (2σ) difference in the calculated transverse target-spin asymmetry in deeply virtual Compton scattering (ρ⁰ electroproduction), where σ is the total experimental uncertainty.