We study large-distance contributions to the nucleon parton densities in the transverse coordinate (impact parameter) representation based on generalized parton distributions (GPDs). Chiral dynamics generates a distinct component of the partonic structure, located at momentum fractions x≲ M πMN and transverse distances b ∼ 1/M π. We analyze the phenomenological "pion cloud" model of the flavor asymmetry d̄(x)-ū(x) and quantify what fraction of the calculated asymmetry results from the universal large-distance region. We show that in this model the region b > bcore ≈ 0.55 fm (the transverse "quark core" radius estimated from the nucleon's axial charge radius) produces only ∼30% of the asymmetry measured in the FNAL E866 experiment at x ∼01. Our findings indicate that the asymmetry originates mostly from the "quark core" at small transverse distances.
|Original language||English (US)|
|Journal||Proceedings of Science|
|State||Published - Dec 1 2008|
|Event||Light Cone 2008 on Relativistic Nuclear and Particle Physics, LC 2008 - Mulhouse, France|
Duration: Jul 7 2008 → Jul 11 2008
All Science Journal Classification (ASJC) codes