Dynamical Axions and Gravitational Waves. (arXiv:1904.10967v1 [hep-ph])
<a href="http://arxiv.org/find/hep-ph/1/au:+Croon_D/0/1/0/all/0/1">Djuna Croon</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Houtz_R/0/1/0/all/0/1">Rachel Houtz</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Sanz_V/0/1/0/all/0/1">Veronica Sanz</a>

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.
We find that the amplitude of the gravitational wave spectrum depends on the
mass of the dynamical axion $eta’$ via the ratio $m_{eta’}/m_varphi$. The
resulting spectra may be observed at future mid-range gravitational wave
experiments such as AION/MAGIS, DECIGO, and BBO. Moreover, the TeV states can
be searched for at colliders and their quantum numbers characterized, providing
a unique connection between axion physics, gravitational waves and collider
searches.

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.
We find that the amplitude of the gravitational wave spectrum depends on the
mass of the dynamical axion $eta’$ via the ratio $m_{eta’}/m_varphi$. The
resulting spectra may be observed at future mid-range gravitational wave
experiments such as AION/MAGIS, DECIGO, and BBO. Moreover, the TeV states can
be searched for at colliders and their quantum numbers characterized, providing
a unique connection between axion physics, gravitational waves and collider
searches.

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