Exclusive production of B_c mesons in e~+e~- colliders

Within the framework of the perturbative QCD approach,we calculate the time-like B_(c )B_c(B_c~*)form factors F(Q~2)and A_2(Q~2).We include relativistic corrections and QCD corrections,either of which can give about20%correction to the leading-order contribution,but there are cancellation effects between them.We calculate the cross sections of the e~+e~-→B_c~-B_c~+(B_c~(*+))processes.The cross sections are enhanced at the Z pole to beσ~(P P)(Q=m _Z)～1.3×10~(-5)pb andσ~(P V)(Q=m _Z)～2.5×10~(-5)pb,which are still too small to be detected by proposed e~+e~-colliders such as the Circular Electron Positron Collider.