Hadron structure function in flux tube model

The quark distribution functions of the meson (q-(q-bar) system) and the nucleon (both q-diquark system and symmetric Y shape system) are calculated using the yo-yo mode of the classical string model. The valence quark distributions of the proton are consistent with intermediate value of q-diquark and symmetric Y shape calculation. Using the Weizsaecker-Williams approximation, the gluon distribution function is obtained from the Poynting vector of the flux tube which has the same energy-momentum relation as the string. (author)