DESY, Platanenalle 6, 15738 Zeuthen n. Berlin, Germany, 18.05.2018

**Organizers:**

Ana Alonso-Serrano (MPI Golm, Germany), Mariusz P. Dąbrowski (chair, Univ. Szczecin, Poland), Thomas Naumann (DESY Zeuthen, Germany)

An idea of the meeting is to unite the groups working on cosmology from University of Szczecin, Albert Einstein MPI Golm, and DESY Zeuthen. This is one-day meeting. The idea is to have more informal talks appended with the extensive discussions. People interested in joining may contact the chair organiser (Mariusz.Dabrowski@usz.edu.pl) about the attendance.

**Participants:**

1. Giovanni Acquaviva (CharlesU, Prague)

2. Ana Alonso-Serrano (MPI, Golm)

3. Teresa Bautista (MPI, Golm)

4. Sebastian Bramberger (MPI, Golm)

5. Sayantan Choudhury (MPI, Golm)

6. Mariusz P. Dąbrowski (USzczecin)

7. Tomasz Denkiewicz (USzczecin)

8. Alice Di Tucci (MPI, Golm)

9. Shane Farnsworth (MPI, Golm)

10. Hussain Gohar (USzczecin)

11. Jean-Luc Lehners (MPI, Golm)

12. Katarzyna Leszczyńska (USzczecin)

13. Thomas Naumann (DESY, Zeuthen)

14. Albin Nilsson (NCBJ, Warsaw)

15. Daniele Oriti (MPI, Golm)

16. Adamantia Zampeli (CharlesU, Prague)

17. Stephen Green (MPI, Golm)

**Programme:**

**Friday, 18.05.2018**

**9.00 – 9.30:** Registration at DESY, Platanenallee 6, 15738 Zeuthen, Room 1, 3rd floor, building H

**9.30 - 10.00:** A. Alonso-Serrano " Black hole information flux"

**10.00 – 10.30:** G. Aquaviva "Emergent scenario from the Bekenstein bound: some implications"

**10.30 - 11.00:** D. Oriti "Possible resolutions of the cosmological singularity in quantum gravity"

**11.00 – 11.30:** Discussion

**11.30 – 12.30:** *Lunch*

**12.30 – 13.00:** J.-L. Lehners "Gravitational path integrals and the early universe"

**13.00 – 13.30:** M. Dąbrowski "Cosmological measurement of the speed of light"

**13.30 – 14.00:** K. Leszczyńska "Varying constants driven baryogenesis"

**14.00 – 14.30:** Discussion

**14.30 – 15.00:** *Coffee*

**15.00 – 15.30:** A. Nilsson "Probing Horava-Lifshitz cosmology"

**15.30 - 16.00:** T. Bautista "Non-local effective actions in Weyl-flat spacetimes"

**16.00 - 16.30:** S. Farnsworth "Spinor driven cosmic bounces and their cosmological perturbations"

**16.30 - 17.00:** S. Choudhury "Inflation to large scale structure: EFT all the way"

**17.00 - 18.00:** Discussion

**18.00 – 19.00:** *Dinner*

**19.00:** Farewell

Talk titles with abstracts:

Daniele Oriti

Title: Possible resolutions of the cosmological singularity in quantum gravity

Abstract: We illustrate the general ideas and recent results in group field theory condensate cosmology, a framework in which cosmological dynamics emerges as the hydrodynamics of the microscopic quantum gravity degrees of freedom. We then focus on the fate of the classical cosmological singularity, in this context, and discuss two ways in which it may be resolved. We also discuss some conceptual and physical issues associated with this resolution and with the whole framework.

Ana Alonso-Serrano:

Title: Black holes information flux

Abstract: We have studied the entropy budget per particle emitted in black hole evaporation process. In order to carry out this calculation we

adopted a variant of the “average subsystem” approach, but consider a tripartite pure system that includes the influence of the rest of

the universe. If the process is unitary, the entropy is exactly compensated by the “hidden information” in the correlations that we

choose not to consider within the specific selected coarse-graining. In addition, the entropy budget should be corrected at the last

stages of evaporation, due to quantum gravity effects. We have been shown recently how these effects (expressed in terms of the

generalized uncertainty principle) modify the Hawking flux when we approach the Planck size.

Giovanni Acquaviva

Title: Emergent scenario from the Bekenstein bound: some implications.

Abstract: The Bekenstein bound states that the entropy of a system contained in a certain volume is bounded from above by the entropy of a black hole with corresponding surface area. We relate such universal bound to the existence of fundamental degrees of freedom and provide model-independent considerations about their features. In particular, both geometry and fields propagating on it are seen as phenomena emergent from the more fundamental dynamics, in analogy with many examples in condensed matter physics. An immediate consequence is that, even though the fundamental evolution is considered unitary, the fields develop an entanglement with the spacetime geometry, hence leading to an effective non-unitary evolution on the emergent level. We exemplify some consequences of this scenario by providing a toy-model of black hole evaporation, in which the entanglement between geometry and fields is interpreted at our low-energy scales as an effective loss of information in Hawking r adiation.

Teresa Bautista

Title: Non-local effective actions in Weyl-flat spacetimes

Abstract: The covariant renormalization of composite operators in the action leads to Weyl anomalies. Consequently, in the quantum effective action, operators exhibit an anomalous dependence on the conformal factor of the metric, which can have interesting consequences for (A)dS and cosmology. In this talk I will show how both this dependence and the full quantum effective action can be easily determined for classically Weyl invariant theories on Weyl-flat spacetimes. The result re-sums the spacetime curvatures of the corresponding Barvinski-Vilkovisky expansion.