Joint Theory Seminar
Speaker: Rachel Houtz
Title: Color Unified Dynamical Axion
Host: John Terning
Room: 432
Abstract: In this talk I present a model with an enlarged color sector which solves the strong CP problem via new massless fermions. Solutions to the strong CP problem with new massless fermions typically introduce a new gauge group which confines to turn the massless fermions into phenomenologically allowed bound states. One of these bound states can then be identified as a dynamical axion. The new group, however, has its own CP-violating theta angle, and so without more model building the strong CP problem remains. In our model, we invoke unification to relate the two theta angles. The spontaneous breaking of the unified color group into QCD and another confining group proves a source of naturally large axion mass due to small size instantons. This model naturally enlarges the axion mass versus axion scale parameter space well beyond that of invisible axion models.
