Theoretical Physics(DTP)
Physique théorique (DPT)

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Luc MARLEAU
Université Laval

Revisiting the Skyrme model

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Proposed more than four decades ago, the Skyrme model was revived in the 80's in the context of the 1/N_c expansion and more recently, have regain attention since it could provide a explanation for newly discovered hadronic states. As a non-linear theory of pions, it provides an approximate description of hadronic physics in the low-energy limit. In this theory, the nucleon emerges as a non perturbative solution of the field equations, or more precisely as a soliton. It is also seen as a prototype model in various physical contexts (e.g. condensed matter, wrapped branes) where one could expect soliton solutions to occur.

The original Skyrme Lagrangian is a naive extension of the non-linear sigma model consisting of a fourth-order field derivatives term. This is nonetheless sufficient to stabilize the soliton against scale transformations and to reach at least a 30% accuracy with respect to physical observables. In order to incorporate effects due to higher-spin mesons and improve the fit on most observables a number of alternative Skyrme-like models which preserved the form of the original Lagrangian while extending it to higher orders has been proposed and analyzed.

We describe some of these extensions of the model and several attempts to obtain single- and multi-skyrmion solutions.