  Spectral densities are computed in unprecedented detail for quantum
antiferromagnetic spin 1/2 two-leg ladders. These results were obtained due to
a major methodical advance achieved by optimally chosen unitary
transformations. The approach is based on dressed integer excitations.
Considerable weight is found at high energies in the two-particle sector.
Precursors of fractional spinon physics occur implying that there is no
necessity to resort to fractional excitations in order to describe features at
higher energies.
