Two-Pion Exchange Interaction Between Constituent Quarks

TL;DR

This paper investigates the two-pion exchange interaction between constituent quarks, showing it enhances certain spin-spin effects and cancels tensor components, helping explain hyperfine interactions in hadrons.

Contribution

It provides a detailed analysis of two-pion exchange effects, highlighting their role in modifying hyperfine interactions and spin-orbit components in constituent quark models.

Findings

Enhances isospin dependent spin-spin interactions

Cancels tensor components of one-pion exchange

Strengthens spin-orbit interaction with opposite sign

Abstract

The two-pion exchange interaction between constituent quarks is shown to enhance the effect of the the isospin dependent spin-spin component of the one-pion exchange interaction, and to cancel out its tensor component. It therefore provides a partial explanation for the phenomenological observation that the hyperfine interaction between constituent quarks is well described by a flavor dependent spin-spin interaction, which is attractive at short and repulsive at long range. The spin-orbit component of the two-pion exchange interaction is stronger than and has the opposite sign from that associated with the linear confining interaction in the $P-$shell multiplets.