Waves and Solitons in the Calogero Model - Revisited

TL;DR

This paper revisits periodic solutions of the Calogero model's collective field equations, including density waves and solitons, and extends the analysis to a two-family generalization, providing new insights and mathematical tools.

Contribution

It offers a detailed analysis of periodic solutions in the Calogero model and its two-family extension, enhancing understanding of density waves and solitons in these systems.

Findings

Periodic solutions exist in the Calogero model and its two-family generalization.

The solutions include finite amplitude density waves and large amplitude density waves.

Mathematical identities related to Hilbert transforms are established and utilized.

Abstract

The Calogero model bears, in the continuum limit, collective excitations in the form of density waves and solitary modulations of the density of particles. This sector of the spectrum of the model was investigated, mostly within the framework of collective field theory, by several authors, over the past fifteen years or so. In this work we shall concentrate on periodic solutions of the collective BPS-equation (also known as "finite amplitude density waves"), as well as on periodic solutions of the full static variational equations which vanish periodically (also known as "large amplitude density waves"). While these solutions are not new, we feel that our analysis and presentation add to the existing literature, as we explain in the text. In addition, we show that these solutions also occur in a certain two-family generalization of the Calogero model, at special points in parameter space. A compendium of useful identities associated with Hilbert transforms, including our own proofs of these identities, appears in Appendix A. In Appendix B we also elucidate in the present paper some fine points having to do with manipulating Hilbert transforms, which appear ubiquitously in the collective field formalism. Finally, in order to make this paper self-contained, we briefly summarize in Appendix C basic facts about the collective field formulation of the Calogero model.