Mass Effects On The Nucleon Sea Structure Functions

Abstract

Nucleon sea structure functions are studied using Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) equations with the massive gluon-quark splitting kernels for strange and charm quarks, the massless gluon-quark splitting kernels for up and down quarks, and the massless kernels for all other splitting parts. The $SU(2)_f$ flavor symmetry for two light quarks, `up' and `down', is assumed. Gl\"uck-Reya-Vogt(GRV) and Martin-Roberts-Stirling(MRS) sets are chosen to be the base structure functions at $Q_0^2=3$GeV$^2$. We evolve the sea structure functions from $Q_0^2=3$ GeV$^2$ to $Q^2=50$ GeV$^2$ using the base structure function sets and DGLAP equations. Some (about 10%) enhancement is found in the strange quark distribution functions at low $x(<0.1)$ in leading order of the DGLAP equations compared to results direclty from those structure function sets at the the value of $Q^2=50$ GeV$^2$. We provide the value of $\kappa$ and also show the behavior of $\kappa(x)=2s(x)/(\bar u(x) + \bar d(x))$ after the evolution of structure functions.