Quark-antiquark correlation in the pion

The electromagnetic tensor for inclusive electron scattering off the pion W-mu nu for momentum transfers such that q(+) = 0, (q(+) = q(0) + q(3)) is shown to obey a sum-rule for the component W++. From this sum-rule, one can define the quark-antiquark correlation function in the pion, which characterizes the transverse distance distribution between the quark and antiquark in the light-front pion wave-function. Within the realistic models of the relativistic pion wave function (including instanton vacuum inspired wave function) it is shown that the value of the two-quark correlation radius (r(q (q) over bar)) is near twice the pion electromagnetic radius (r pi), where r pi approximate to 2/3 fm. We also define the correlation length l(corr) where the two-particle correlation have an extremum. The estimation of l(corr) approximate to 0.3-0.5 fm is very close to estimations from instanton models of QCD vacuum. It is also shown that the above correlation is very sensitive to the pion light-front wave-function models. (C) 1997 Elsevier Science B.V.