Unparticle Example in 2D

We discuss what can be learned about unparticle physics by studying simple quantum field theories in one space and one time dimension. We argue that the exactly soluble 2D theory of a massless fermion coupled to a massive vector boson, the Sommerfield model, is an interesting analog of a Banks-Zaks model, approaching a free theory at high energies and a scale-invariant theory with nontrivial anomalous dimensions at low energies. We construct a toy standard model coupling to the fermions in the Sommerfield model and study how the transition from unparticle behavior at low energies to free particle behavior at high energies manifests itself in interactions with the toy standard model particles.

Figure 1

A disappearance process.

Figure 2

Phase space $\Phi$ for the disappearance process in Fig. 1 as a function of the energy $\sqrt{s}$ (in units of $m$) for $a=-0.1$.