Gravitational Waves from First-Order Phase Transition in a Simple Axion-Like Particle Model

P. S. Bhupal Dev, Francesc Ferrer, Yiyang Zhang +1

We consider a gauge-singlet complex scalar field $\Phi$ with a global $U(1)$ symmetry that is spontaneously broken at some high energy scale $f_a$. As a result, the angular part of th…