Cosmology of bifundamental fields

If a field theory contains gauged, non-Abelian, bifundamental fields, i.e. fields that are charged under two separate non-Abelian gauge groups, the transition from a deconfined phase to a hadronic phase may be frustrated. Similar frustration may occur in non-Abelian gauge models containing matter only in higher dimensional representations, e.g. models with pure glue, or if ordinary quarks are confined by two flux tubes, as implied in the triangular configuration of baryons within QCD. In a cosmological setting, such models can lead to the formation of a web of confining electric flux tubes that can potentially have observational signatures.

Figure 1

Baryons consist of 3 or more bifundamentals (solid black circle), each confined by two types of flux tubes. The flux tubes of each type in a baryon may be in a Y configuration (upper drawing) or a triangular configuration (lower drawing). Mesons consist of a particle and an antiparticle.

Figure 2

The web of bifundamentals. Two types of flux tubes connect each particle, and the network percolates, forming an infinite web.

Figure 3

The plot shows the schematic evolution of cosmic energy densities for the radiation ($r$), matter ($m$), and cosmological constant ($c$). The web energy density is shown by the dashed lines, each line assuming a different initial density. If the initial energy density in the web is larger than that of the matter component, the universe enters a web-dominated epoch and never a matter-dominated epoch. With smaller initial energy density (middle dashed line), the web can dominate at recent epochs, prior to cosmological constant domination. With yet smaller initial energy density, the web remains subdominant throughout.