5 papers
Anomaly-free axion-like particle in Nelson-Barr models
Mohammad Aghaie, Ryoma Masuda, Ryosuke Sato
We study Nelson--Barr models with a discrete symmetry that solve the strong CP problem through spontaneous CP violation, and show that they naturally predict a light axion-li…
Generalizations and UV completions of Cho-Maison monopole
Fukutaro Miya, Ryosuke Sato
A monopole configuration in the electroweak theory was constructed by Cho and Maison, allowing for a singular behavior at the origin. Since the essential structure of the Cho-Maiso…
Sommerfeld enhancement from unstable final-state particles in dark matter annihilation
Tomohiro Abe, Ryosuke Sato, Takumu Yamanaka
We study the Sommerfeld enhancement of the annihilation cross section of dark matter into heavier unstable particles. In this process, the annihilation products become non-relativi…
New Source for QCD Axion Dark Matter Production: Curvature Induced
Cem Eröncel, Yann Gouttenoire, Ryosuke Sato +2
We discuss a novel mechanism for generating dark matter from a fast-rolling scalar field, relevant for both inflation and rotating axion models, and apply it specifically to the (Q…
A universal bound on the duration of a kination era
Cem Eröncel, Yann Gouttenoire, Ryosuke Sato +2
We show that primordial adiabatic curvature fluctuations generate an instability of the scalar field sourcing a kination era. We demonstrate that the generated higher Fourier modes…