135 citations · 445 across the 12 of their papers we have counts for
12 papers
Probing the primordial universe with gravitational waves detectors
Yu-Tong Wang, Yong Cai, Zhi-Guo Liu +1
The spectrum of primordial gravitational waves (GWs), especially its tilt , carries significant information about the primordial universe. Combining recent aLIGO and Planck201…
Pre-inflationary genesis with CMB B-mode polarization
Zhi-Guo Liu, Hong Li, Yun-Song Piao
Recent B-mode polarization observation seems to imply the tensor tilt at large angular scale, if the primordial signal is dominated. We show that for a primordial un…
AdS cycles in eternally inflating background
Zhi-Guo Liu, Yun-Song Piao
In the eternally inflating background, the bubbles with AdS vacua will crunch. However, this crunch might be followed by a bounce. It is generally thought that the bubble universe…
CMB anomalies from an inflationary model in string theory
Zhi-Guo Liu, Zong-Kuan Guo, Yun-Song Piao
Recent Planck measurements show some CMB anomalies on large angular scales, which confirms the early observations by WMAP. We show that an inflationary model, in which before the s…
Obtaining the CMB anomalies with a bounce from the contracting phase to inflation
Zhi-Guo Liu, Zong-Kuan Guo, Yun-Song Piao
Recent Planck data show the anomalies of CMB fluctuations on large angular scales, which confirms the early observations by WMAP. We continue studying an inflationary model, in whi…
Galilean Islands in Eternally Inflating Background
Zhi-Guo Liu, Yun-Song Piao
We show that the observational universe may emerge classically from a de Sitter background with low energy scale. We find, after calculating the curvature perturbation, that the re…
A Galileon Design of Slow Expansion: II
Zhi-Guo Liu, Yun-Song Piao
We parameterize the evolutions of the slow expansion, which emerges from a static state in infinite past, into different classes. We show that the scale invariant adiabatical pertu…
Phantom Inflation in Little Rip
Zhi-Guo Liu, Yun-Song Piao
We study the phantom inflation in little rip cosmology, in which the current acceleration is driven by the field with the parameter of state w < -1, but since w tends to -1 asympto…
Scalar Perturbations Through Cycles
Zhi-Guo Liu, Yun-Song Piao
We analytically and numerically investigate the evolutions of the scalar perturbations through the cycles with nonsingular bounce. It is found that the amplitude of the curvature p…
A Galileon Design of Slow Expansion
Zhi-Guo Liu, Jun Zhang, Yun-Song Piao
We show a model of the slow expansion, in which the scale invariant spectrum of curvature perturbation is adiabatically induced by its increasing mode, by applying a generalized Ga…
Phantom Inflation with A Steplike Potential
Zhi-Guo Liu, Jun Zhang, Yun-Song Piao
The phantom inflation predicts a slightly blue spectrum of tensor perturbation, which might be tested in coming observations. In normal inflation models, the introduction of step i…
Amplification of Curvature Perturbations in Cyclic Cosmology
Jun Zhang, Zhi-Guo Liu, Yun-Song Piao
We analytically and numerically show that through the cycles with nonsingular bounce the amplitude of curvature perturbation on large scale will be amplified and the power spectrum…