Quark exchange and valence quark distributions in A=3 mirror nuclei

The quark-exchange formalism for nuclear systems is reformulated to treat the proton, neutron and up and down quarks explicitly and it is used to calculate the structure functions of A=3 mirror nuclei, i.e., 3He and 3H nuclei. The solution of Faddeev equations is used as the three nucleon system wave function and the initial valence quark input are taken from the GRV's (Glück, Reya and Vogt) next-to-leading order QCD calculations on which give very good fits to the available data in the (x,Q2)-plane. The momentum distributions of 3He, 3H and isoscalar A=3 systems as well as up and down quarks are discussed. It is shown that the quark-exchange has a sizable contribution to the structure functions of A=3 systems. So it is concluded that the nuclear structure effect is still important in 3He and 3H nuclei and the spectral functions based on the naive impulse approximation are not enough to extract the neutron structure function from these nuclei. These phenomena can be tested by the future deep inelastic electron experiments on 3He and 3H nuclei, especially those expected from the proposed 11 GeV Jefferson Laboratory.