Basic features of the pion valence-quark distribution function

2014/06/20 by Lei Chang, Cédric Mezrag, Hervé Moutarde +3 · 1 citation
Physics and Astronomy · #nucl-th #hep-ex #hep-lat #hep-ph #nucl-ex

paper · pdf · doi:10.1016/j.physletb.2014.08.009

7 pages, 5 figures

arxiv created 2014/06/20 · arxiv updated 2014/08/20

Abstract

The impulse-approximation expression used hitherto to define the pion's valence-quark distribution function is flawed because it omits contributions from the gluons which bind quarks into the pion. A corrected leading-order expression produces the model-independent result that quarks dressed via the rainbow-ladder truncation, or any practical analogue, carry all the pion's light-front momentum at a characteristic hadronic scale. Corrections to the leading contribution may be divided into two classes, responsible for shifting dressed-quark momentum into glue and sea-quarks. Working with available empirical information, we use an algebraic model to express the principal impact of both classes of corrections. This enables a realistic comparison with experiment that allows us to highlight the basic features of the pion's measurable valence-quark distribution, q^π(x); namely, at a characteristic hadronic scale, q^π(x) ∼ (1-x)² for x\gtrsim 0.85; and the valence-quarks carry approximately two-thirds of the pion's light-front momentum.

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