Furthermore, ϕ ϕ μ μ 1 ν ν 1 are considered to be the basis states of D ( p 1 , q 1 ) and ϕ ϕ μ μ 2 ν ν 2 are the basis states of D ( p 2 , q 2 ) . Also ϕ ϕ μ μ 1 ν ν 1 , ϕ ϕ μ μ 2 ν ν 2 are the basis states of the product representation. Here ν ν 1 , ν ν 2 represents the combined eigenvalues ( i 2 1 , i z 1 , y 1 ) and ( i 2 2 , i z 2 , y 2 ) respectively.