Dynamical Axions and Gravitational Waves

Understand

In this paper we explore the possibility of observable gravitational waves as a manifestation of the QCD axion dynamics.

• In particular, we focus on dynamical axion models which solve the strong CP problem, and include the confinement of a QCD-like gauge group at the TeV scale.
• We study the resulting chiral symmetry breaking phase transition for models with $N_F=3$ and $N_F=4$ light flavors using the linear sigma model.
• This model describes the scalar meson spectrum and its interactions, with the diagonal field $\varphi$ as the order parameter.