Open Access
Volume 88, Number 6, December 2009
Article Number 61001
Number of page(s) 5
Section The Physics of Elementary Particles and Fields
Published online 01 January 2010
EPL, 88 (2009) 61001
DOI: 10.1209/0295-5075/88/61001

Intrinsic quark transverse momentum in the nucleon from lattice QCD

Ph. Hägler1, B. U. Musch1, J. W. Negele2 and A. Schäfer3

1   Institut für Theoretische Physik T39, Physik-Department der TU München - 85747 Garching, Germany, EU
2   Center for Theoretical Physics, Massachusetts Institute of Technology - Cambridge, MA 02139, USA
3   Institut für Theoretische Physik, Universität Regensburg - 93040 Regensburg, Germany, EU

received 14 October 2009; accepted in final form 22 November 2009; published December 2009
published online 4 January 2010

A better understanding of transverse momentum $(\vect{ k}_{\perp})$ dependent quark distributions in a hadron is needed to interpret several experimentally observed large angular asymmetries and to clarify the fundamental role of gauge links in non-Abelian gauge theories. Based on manifestly non-local gauge-invariant quark operators we introduce process-independent $\vect{ k}_{\perp }$ distributions and study their properties in lattice QCD. We find that the longitudinal and transverse momentum dependence approximately factorize, in contrast to the behavior of generalized parton distributions. The resulting quark $\vect{ k}_{\perp }$ probability densities for the nucleon show characteristic dipole deformations due to correlations between intrinsic $\vect{ k}_{\perp }$ and the quark or nucleon spin. Our lattice calculations are based on Nf = 2+1 mixed action propagators of the LHP Collaboration.

12.38.Gc - Lattice QCD calculations.
14.20.Dh - Protons and neutrons.

© EPLA 2009