Why and how to make constituent and current quarks different - and the how to forget them both

In the absence of SU(6)/sub W/ invariance breaking the symmetry generators, which classify hadronic states into degenerate SU(6)/sub W / multiplets, may be identified with the good components of observable local non-conserved currents integrated over a null plane (the light- like charges Q/sup alpha /, Q/sup alpha //sub i/), as is suggested by the free quark model. The breakdown of both SU(6)/sub W/ and SU(3) invariance of the Hamiltonian requires the existence of a unitary transformation U not=1, which distinguishes and relates the observable light-like charges Q/sup alpha /, Q/sup alpha //sub i/ and the symmetry operators W/sup alpha /, W/sup alpha //sub i/, classifying the observed hadrons into mass non-degenerate SU(6)/sub W/ multiplets. A general form of the transformation U is constructed in a broad class of quark field theories and it is then used to abstract from these theories new algebraic structures, which describe the effects of SU(6) /sub W/ and SU(3) invariance breaking on certain observables. Some predictions valid in the invariance limit remain unaffected to all orders of SU(6)/sub W/ and SU(3) invariance breaking, some are improved and some are completely removed. (24 refs).