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Preliminaries on a Lattice Analysis of The Pion Light-cone Wave function: a Partonic Signal?

A. Abada, Ph. Boucaud, G. Herdoiza, J. P. Leroy, J. Micheli, O. Pène, J. Rodríguez-Quintero

hep-pharXiv:hep-ph/0105221

Abstract

We present the first attempt of a new method to compute the pion light-cone wave function (LCWF) on the lattice. We compute the matrix element between the pion and the vacuum of a non-local operator: the propagator of a ``scalar quark'' (named for short "squark"). A theoretical analysis shows that for some kinematical conditions (energetic pion and hard squark) this matrix element depends dominantly on the LCWF Φπ(u), u∈ [0,1]. On the lattice, the discretization of the parton momenta imposes further constraints on the pion momentum. The two-point Green functions made of squark-quark and squark-squark fields show hadron-like bound-state behaviour and verify the standard energy spectrum. We show some indications that during a short time, after being created, the system of the spectator quark and the squark behave like partons, before they form a hadron-like bound state. This short time is the place where the partonic wave function has to be looked for.

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