7 papers
Axion Inflation from Heavy-Fermion One-Loop Effects
Kai-Ge Zhang, Jian-Feng He, Chengjie Fu +1
We derive a one-loop effective description of axion inflation by integrating out a heavy Dirac fermion with an inflaton-dependent complex mass undergoing a smooth localized thresho…
Localized Steps toward ACT-Favored Inflation
Kai-Ge Zhang, Chengjie Fu, Jian-Feng He +1
Recent ACT measurements favor a scalar spectral index larger than the Planck value, posing a challenge to many single-field slow-roll inflation models. We show that a smooth, local…
Suppression of scalar perturbations due to a heavy axion
Kai-Ge Zhang, Jian-Feng He, Chengjie Fu +1
A fast-rolling axion can transfer its kinetic energy to gauge fields via the Chern-Simons coupling, leading to copious production of gauge quanta during inflation. The amplified ga…
Ring formation from black hole superradiance through repeated particle production on bound orbits
Zhen-Hong Lyu, Rong-Gen Cai, Zong-Kuan Guo +2
Ultralight bosonic fields around a rotating black hole can extract energy and angular momentum through the superradiant instability and form a dense cloud. We investigate the scena…
Gravitational Waves from Gauge Quanta Produced during Inflation
Kai-Ge Zhang, Jian-Feng He, Chengjie Fu +1
A fast-rolling axion can transfer its kinetic energy to a gauge field via the Chern-Simons coupling, leading to copious production of gauge quanta, which can act as a source of gra…
Strong backreaction of gauge quanta produced during inflation
Jian-Feng He, Kai-Ge Zhang, Chengjie Fu +1
During inflation an axion field coupled to a gauge field through a Chern-Simons term can trigger the production of gauge quanta due to a tachyonic instability. The amplification of…