Center for Theory of Quantum Matter Seminar

Confinement and mass generation without Goldstone Bosons: a new paradigm, presented by Professor Anna Hasenfratz Strongly coupled gauge theories are usually expected either to remain conformal or to generate a mass gap through spontaneous chiral symmetry breaking, accompanied by Goldstone bosons. I will discuss evidence for a different possibility in four-dimensional gauge-fermion systems: a confining, fully gapped phase with no bilinear chiral condensate and no Goldstone modes. This behavior is observed in massless SU(2) gauge theory with N_f=4)and SU(3) gauge theory with N_f=8, flavors, using staggered fermions. I will describe the role of taste-breaking interactions and the corresponding continuum effective theory, and review evidence that the transition between the gapped and conformal phases is continuous and possibly associated with a merger of infrared and ultraviolet fixed points. These systems may therefore define new strongly coupled continuum quantum field theories and sugge...