Infrared phase of SU(2) gauge theory with two adjoint Weyl fermions
In plain words
A close relative of QCD, with matter particles of a different type, has several candidate behaviors at long distances. Which one it chooses is unknown.
Precise statement
4D $\mathrm{SU}(2)$ gauge theory with two massless Weyl fermions in the adjoint representation (equivalently one adjoint Dirac fermion) has $\mathrm{SU}(2)_{R}$ flavor and $Z_{8}$ discrete chiral symmetry. Determine its deep-infrared phase among the candidates: confinement with $\mathrm{SU}(2)_{R} \to \mathrm{U}(1)$ breaking (a $\mathrm{CP}^{1}$ sigma model), confinement with massless composite fermions, or an interacting CFT (Cordova and Dumitrescu 2018; Anber and Poppitz 2018).
What would settle it
Lattice simulation of SU(2) with one adjoint Dirac fermion at small mass and large volume, measuring the spectrum, chiral condensate and mass anomalous dimension.
Status in the literature
Unverified note
Lattice studies (2014-2024) report near-conformal spectra with a large mass anomalous dimension, not conclusive between the candidates.