An Explicit Basis for the Reduction U(n + m) ↓ U(n) × U(m)
Jouko Mickelsson · Journal of Mathematical Physics · 1971
We construct lowering operators associated with the multiplicity pattern obtained in a previous paper [J. Math. Phys. 11, 2803 (1970)] for the labeling of the basis vectors in the reduction of an irreducible representation of U(n + m) with respect to U(n) × U(m). Every basis vector can be written as a product of lowering operators acting on the highest-weight vector.