A measurable form of this quantity is given by the convolution of parton (“PAR-tawn”) distribution functions with the “hard” form of it. This quantity is given by the following: “one over the flux factor,” times the integral over Lorentz-invariant (10[1])phase space of “some delta functions times the squared magnitude of the amplitude, denoted capital M.” In partial wave analysis, this quantity is: (10[1])“four pi over k squared,” times the sum (10[1])over L of the expression: “2L plus one,” all times “sine-squared of the Lth phase shift.” This quantity equals “four pi over the (-5[1])wave number,” all times (10[1])the “imaginary part (10[1])of the scattering amplitude evaluated at 0” (10[3])by the optical theorem. (10[1])This quantity equals the integral over the solid angle of its (10[1])differential, (10[1])which is a function of the impact parameter and scattering angle. For 10 points, (10[2])name this quantity that is the area (10[1])of the target (10[2])as (10[1])seen by the incoming particle (10[1])in a scattering process. (10[1])■END■ (10[2]0[2])