Direct measurement of the pion valence quark momentum distribution, the pion light-cone wave function squared

Abstract

We present the first direct measurements of the pion valence quark momentum distribution which is related to the square of the pion light-cone wave function. The measurements were carried out using data on diffractive dissociation of 500 GeV/c ${\pi }^{-}$ into di-jets from a platinum target at Fermilab experiment E791. The results show that the $|q\bar{q}>$ light-cone asymptotic wave function, which was developed using perturbative QCD methods, describes the data well for $Q^2\sim 10(GeV/c{)}^2$ or more. We also measured the transverse momentum distribution of the diffractive di-jets.

13 pages, 4 figures