Pion cloud and sea quark flavor asymmetry in the impact parameter representation

Understand

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_pi/M_N and transverse distances b ~ 1/M_pi.
• We analyze the phenomenological &#34;pion cloud&#34; model of the flavor asymmetry dbar(x) - ubar(x) and quantify what fraction of the calculated asymmetry results from the universal large-distance region.
• Our findings indicate that a two-component picture of the nucleon's partonic structure, with a &#34;core&#34; antiquark distribution at b < b_core ~= 0.55 fm which vanishes at x -> 0 and the universal large-distance pion cloud, could naturally account for the x-dependence of the measured asymmetry.