1pm - 2pm: Confinement and mass generation without Goldstone Bosons: a new paradigm

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 numerical 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), 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 suggest a broader paradigm for mass generation in four dimensions.