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Description
In some proposed condensed matter systems, SU(2) with one massless adjoint Dirac quark flavor emerges as an effective theory of the critical point. Condensed matter theorists Bi and Senthil have conjectured that a composite fermion composed of two quarks and an antiquark becomes massless and non-interacting as the quark mass goes to zero, whereas the other particles in the theory all have masses bounded away from zero. In contrast, a previous lattice study by Athenodorou et al. suggests that SU(2) with one adjoint Dirac flavor is a conformal theory, so the entire spectrum becomes massless as the quark mass vanishes. A third possibility is that the theory undergoes spontaneous symmetry breaking, with a single Goldstone boson (the scalar diquark) and its antiparticle going light. Here, we expand upon Athenodorou's investigation by including the composite fermion and a larger range of quark masses in order to determine which of these three potential scenarios accurately describes the theory.
