X2 series of universal quantum dimensions
The antisymmetric square of the adjoint representation of any simple Lie algebra is equal to the sum of adjoint and X2 representations. We present universal formulae for quantum dimensions of an arbitrary Cartan power of X2, and analyze them for singular cases and permuted universal Vogel’s parameters. X2 has been the only representation in the decomposition of the square of the adjoint with unknown universal series. Application to universal knot polynomials is discussed.