BOSONS
?sym = [Xa(r1)*Xb(r2) + Xb(r1)*Xa(r2) ]* T(t)
Those particles that work with the symmetric form are called BOSONS. All of these particles have integer spin as well. Note that if electron 1 and electron 2 both have the same state, ? > 0. This means that both particles CAN be in the same state at the same location at the same time.