FROM PARTONS TO CONSTITUENT QUARKS

We discuss the moments of the proton structure functions F2(x) and g1(x) via the operator-product formalism. We introduce an effective mass for the quarks through an equation of motion. Making use of this, we show that successive moments of a structure function are related to one another in a simple manner. Specifically, the ratios of successive moments depend only on the square of the mass parameter so introduced, and not on the explicit operator matrix elements themselves. Experimental data on the moments indicate that this mass is around 300 MeV, of the order of the constituent quark mass. We strengthen our results by evaluating the moments in a bag model with massive nonstrange quarks.