SEA QUARK TRANSVERSE MOMENTUM DISTRIBUTIONS AND DYNAMICAL CHIRAL SYMMETRY BREAKING

Recent theoretical studies have provided new insight into the intrinsic transverse momentum distributions of valence and sea quarks in the nucleon at a low scale. The valence quark transverse momentum distributions ( $q - \bar q$ ) are governed by the nucleon's inverse hadronic size R-1 ~ 0.2 GeV and drop steeply at large pT. The sea quark distributions ( $\bar q$ ) are in large part generated by non–perturbative chiral–symmetry breaking interactions and extend up to the scale ρ-1 ~ 0.6 GeV. These findings have many implications for modeling the initial conditions of perturbative QCD evolution of TMD distributions (starting scale, shape of pT distributions, coordinate–space correlation functions). The qualitative difference between valence and sea quark intrinsic pT distributions could be observed experimentally, by comparing the transverse momentum distributions of selected hadrons in semi–inclusive deep–inelastic scattering, or those of dileptons produced in pp and $\bar p p$ scattering.