Explicitly covariant analytical expressions for transitional currents of spin-(1/2) particles

Summary

We show that bispinor bilinear forms u_α(p, s)¯u_Β(p′, s′), u_α(p, s)¯v_Β(p′, s′), v_α(p, s)¯u_Β(p′, s′), and v_α(p, s)¯v_Β (p′, s′) can be expressed up to a phase factor as explicitly covariant foldings of the four-vectors,p, p′ (momenta) ands, s′ (polarizations) with the Dirac gamma-matrices. Using these expressions a complete list of the analytical expressions for the transitional currents of spin-(l /2) particles is derived.