High Energy Theory Seminar

I will consider the Renormalization Group flow of Quantum Electrodynamics in $d=3$ coupled to $N_f$ flavors of fermions. For $N_f$ smaller than a critical value $N_f^c$, chiral symmetry breaking is believed to take place. For $N_f > N_f^c$, the theory flows to an interacting fixed point that can be studied in the epsilon-expansion, using the fixed point in $d=4-2\epsilon$. I will discuss the computation of the anomalous dimensions of fermion bilinears and quadrilinear operators, and the enhancement of global symmetries in $d=3$. For small $N_f$, a quadrilinear operator can become relevant in the IR and destabilize the fixed point. Therefore, the epsilon-expansion can be used to estimate $N_f^c$.