3 papers
astro-ph.CO2020
Is the NANOGrav signal a hint of dS decay during inflation?
Hao-Hao Li, Gen Ye, Yun-Song Piao
As suggested by the swampland conjectures, de Sitter (dS) space might be highly unstable if it exists at all. During inflation, the short-lived dS states will decay through a casca…
gr-qc2019
Trans-Planckian censorship of multistage inflation and dark energy
Hao-Hao Li, Gen Ye, Yong Cai +1
We explore the bound of the trans-Planckian censorship conjecture on an inflation model with multiple stages. We show that if the first inflationary stage is responsible for the pr…
gr-qc2019
Time crystals in primordial perturbations
Hao-Hao Li, Yun-Song Piao
Cosmological time crystal (TC) corresponds to a matter state where the periodic motion of field forms a limit cycle in its phase space. We explore what would happen if it existed i…