Bose analogs of MIT bag model of hadrons in coherent precession
  Recently it was demonstrated that magnon condensation in the trap exhibits the phenomenon of self-localization. When the number of magnons in the textural trap increases, they drastically modify the profile of the gap and highly increase its size. The trap gradually transforms from the initial harmonic one to the box with walls almost impenetrable for magnons. The resulting texture-free "cavity" filled by the magnon condensate wave function becomes the bosonic analog of the MIT bag, in which hadron is seen as a cavity surrounded by the QCD vacuum, in which the free quarks are confined in the ground or excited state. Here we consider the bosonic analog of the MIT bag with quarks on the ground and excited levels. 
S. Autti, V. B. Eltsov and G. E. Volovik
cond-mat.other