### Conveners

#### Beyond IV

- Misao Sasaki (morning)
- Yifu Cai (afternoon)

I will give a brief review of inflationary cosmology, including its motivation, observational status, the problem of initial conditions, and the string landscape scenario. I will also describe the problems with hilltop inflation and then I will show that the theory of alpha-attractors and D-brane inflation together can completely cover the range or values of n_s and r favored by Planck 2018.

The inflationary paradigm, already in its simplest disguises, has been spectacularly successful when it comes to agreement with observations. However, there’s a lot we do not yet know about inflation:

- what is its energy scale?

- how about its particle content?

- how did inflation begin?

…

New cosmological probes (at all scales, from CMB to interferometers) will soon put some of our best...

Tests of primordial non-Gaussianity (PNG) are a powerful tool to shed light on the physics of the Early Universe. Currently, the best limits on PNG come from Planck measurements of Cosmic Microwave Background (CMB) temperature and polarization anisotropies, which nearly saturated the CMB constraining power. After briefly reviewing current Planck PNG bounds for a variety of models, I will...

Multi-field inflation with curved field manifold attracts a lot of attention recently. From theoretical aspect, this class of models may be more naturally realized in the UV completion of inflation. From observational point of view, however, the current constraints on primordial non-Gaussianity and isocurvature perturbation already/marginally ruled out many of these models. In this talk I will...

We review quasi-single field inflation and the cosmological collider physics, emphasizing on recent progress. The cosmological collider is a model-independent way of extracting the mass and spin information of heavy particles at the energy scale of inflation. The same mechanism can also be used as a direct probe of the expansion history of the universe. After the introduction, we survey the...

How to model-independently distinguish the inflation scenario from alternatives to inflation is an important challenge in modern cosmology. In this talk, we show that massive fields in the primordial universe function as standard clocks and imprint clock signals in the density perturbations, which directly record the scale factor of the universe as a function of time, a(t). This function is...

We study the back-reaction of the infrared modes of an O(N) scalar theory in a classical de Sitter background. We use the nonperturbative renormalization group methods to extract analytically the flow of the Hubble constant as the gravitationally enhanced long wavelength modes are integrated out. For a massless theory, the interactions tend to renormalize negatively the Hubble constant, thus...

We show how a pair of field theory monodromies in which the shift symmetry is broken by small, well motivated deformations, naturally incorporates a mechanism for cancelling off radiative corrections to the cosmological constant. The lighter monodromy sector plays the role of inflation as well as providing a rigid degree of freedom that acts as a dynamical counterterm for the cosmological...

Cosmic inflation is a period of accelerated expansion in the Early Universe. Inflation is the most compelling proposal for the formation of of the observed structures in the Universe like galaxies and galactic clusters. It also makes the Universe uniform and spatially flat in agreement with observations. To drive inflation an exotic substance is needed, with pressure negative enough to cause...

A rigorous constraint analysis on inflationary cosmology entails several probes which collectively survey an extensive range of energy scales. We complement the current cosmic microwave background data with an updated compilation of the cosmic abundance limits of primordial black holes, with which we infer stringent constraints on the runnings of the scalar spectral index. The constraints on...

I will present the idea of combinig the constant roll inflation with the warm inflationary paradigm, which comes from the strong particle production during inflation. I will show how to solve such a system and I will rpesent fundamental applications of this theory: from inflation to primordial black holes production