Constituent Quarks and the Spin of the Proton

TL;DR

This paper explores the internal structure of constituent quarks and their relation to the proton's spin, revealing that gluons contribute significantly to the quark's spin composition.

Contribution

It introduces a model linking the proton's spin structure to that of constituent quarks, supported by experimental evidence.

Findings

Approximately 30% of a constituent quark's spin is from valence quarks.

Gluons contribute about 70% to the constituent quark's spin.

Experimental data supports the internal structure hypothesis.

Abstract

The constituent quarks are interpreted as bound states, which have an internal structure. The quark distributions of the proton are related to those of the constituent quarks. The experiments support this hypothesis. Likewise the spin structure of the proton is related to the spin structure of the constituent quarks. We find that about 30% of the spin of a constituent quark is given by the valence quark, and 70% are provided by the gluons.