Autumn workshop on gravity and cosmology

Contribution List

2. Reconstruct the history of the universe in f(T) gravity through observational data

Xin Ren (University of Science and Technology of China)

12/11/2019, 09:30

Describing the accelerating expansion of the universe and understanding its causes is an important part of modern cosmology. In order to better understand the evolution form and physical nature of accelerated expansion, it is necessary to combine observation with theory to constrain various dark energy models and modified gravity models. We reconstruct the f(T) gravity model with the latest...

10. Precision constraints for dark energy in the gravitational wave era

Johannes Noller (ETH)

12/11/2019, 11:15

In this talk I will sketch how combining new constraints from gravitational wave measurements, traditional observational bounds from cosmology and insights from theoretical particle physics allows us to test gravity with unprecedented precision, in particular zooming in on the nature of dark energy. As an explicit example, I will highlight the interplay between gravitational wave constraints...

4. Cuscuton Gravity as a Classically Stable Limiting Curvature Theory

Jerome Quintin

12/11/2019, 14:00

Finding effective theories of modified gravity that can resolve cosmological singularities and avoid other physical pathologies such as ghost and gradient instabilities has turned out to be a rather difficult task. The concept of limiting curvature, where one bounds a finite number of curvature-invariant functions thanks to constraint equations, is a promising avenue in that direction, but its...

5. Thin shell wormhole associated with black holes and early universe

Aichen Li

12/11/2019, 15:45

Using ideas of perturbation theories of brane cosmology, we first introduce a new method to judge the stabilities of a type of travelable wormholes, namely the thin-shell wormholes constructed by cutting-and-pasting two building-block spacetimes at arbitrary joining shell radius. Then, we will introduce some phenomenological aspects about the wormhole cosmology, especially focus on the...

8. Free discussion

12/11/2019, 16:45

6. TBA

Rene Meyer

13/11/2019, 09:30

7. String Regge trajectory on de Sitter space and implications to inflation

Siyi Zhou

13/11/2019, 11:15

We study the spectrum of semiclassical rotating strings on de Sitter space and its consistency. Even though a naive extrapolation of the linear Regge trajectory on flat space implies a violation of the Higuchi bound (a unitarity bound on the mass of higher-spin particles in de Sitter space), the curved space effects turn out to modify the trajectory to respect the bound. Interestingly, there...

9. Cosmology with compact phase space

Jakub Mielczarek (Jagiellonian Unviersity)

13/11/2019, 14:00

The kinematical phase space of classical gravitational field is flat (affine) and unbounded. In consequence, field variables may tend to infinity leading to appearance of singularities, which plague Einstein's theory of gravity. During the talk the idea of generalizing the theory of gravity by compactification of the phase space will be discussed. We investigate the procedure of...

3. On the uniqueness of general relativity

Francesco Di Filippo (SISSA)

13/11/2019, 15:45

It is frequently quoted in the literature that general relativity is the only nonlinear theory that can be obtained from massless particles of spin 2. Anyway the technical assumptions behind this statement are not often scrutinized. I will discuss what happen when one of these assumptions is relaxed and I will argue that modern on-shell methods provide a convenient mathematical framework for...

11. free discussion

13/11/2019, 16:45

12. The cosmological inconstant and Cartan's spiral staircase

Joao Magueijo

14/11/2019, 09:15

We review recent efforts to turn the cosmological constant into a dynamical variable without an ungainly proliferation of free parameters. In a cosmological setting where parity invariance is imposed (along with homogeneity and isotropy) this leads to phenomenological disaster. However, in this theory it is possible to construct parity violating Friedman models due to torsion, a re-enactment...

13. novel matter coupling in Einstein gravity

Chunshan Lin

14/11/2019, 11:00

The old school knowledge tells us that the matter can couple to Einstein gravity in either minimal or Brans-Dicke manner. Recently we discovered a novel type of matter coupling in Einstein gravity. This type of matter coupling is theoretically self-consistent in the sense that all constraints in the Hamiltonian are preserved to be first class. At low energy scale it recovers the classic...