Diffractive Dissociation of High Momentum Pions

TL;DR

This paper investigates the diffractive dissociation of high-momentum pions into di-jets to measure quark momentum distributions, providing experimental evidence supporting perturbative QCD predictions and observing color transparency effects.

Contribution

It presents experimental data from Fermilab E791 on pion diffractive dissociation, validating the asymptotic wave function and observing color transparency at high Q^2.

Findings

The asymptotic wave function describes the data well at Q^2 ~ 10 (GeV/c)^2.

Evidence of color transparency observed through A-dependence of di-jet yields.

Experimental validation of perturbative QCD predictions for pion structure.

Abstract

The diffractive dissociation of 500 GeV/c $\pi^-$ into di-jets is described as a way to measure the momentum distribution of quarks in the pion. The measurements of the pion diffractive dissociation were carried out using data from Fermilab E791. Preliminary results show that the $|q\bar {q}>$ Asymptotic wave function which was developed using perturbative QCD methods describes the data well for $Q^2 \sim 10 ~{\rm (GeV/c)^2}$. At these values signals of color transparency are expected and, indeed, observed through the $A$-dependence of the yield of the diffractive di-jets.