Cosmology

Understanding the small-scale structure of spacetime is one of the biggest challenges faced by  modern theoretical physics. There are many different attempts to solve this problem and they reflect the diversity of approaches to quantum gravity. This workshop will bring together researchers from a wide range of quantum gravity approaches and give them an opportunity to exchange ideas and gain  new insights.

One of the biggest mysteries in cosmology and fundamental physics is the nature of dark energy that is responsible for the current acceleration of cosmic expansion. While a cosmological constant provides the simplest model of dark energy recent observational tensions amongst supernovae Ia gravitational lensing time delays and cosmic microwave background suggest the need for a more complex dynamical dark energy. One of the oldest proposals for a dynamical dark energy is Everpresent Lambda proposed by Sorkin which is inspired by the causal set model of quantum gravity. It was recently shown that this model can potentially resolve the  tensions in cosmological observations. The meeting aims to bring together a small number of experts in quantum gravity causal sets and cosmology to carefully examine the models theoretical predictions and its observational tests and pave the way for what might be an(other) exciting insight from cosmology into the fundamental nature of spacetime.

This cross-disciplinary workshop gathers theorists who have been working on novel approaches to understanding the structure of the Standard Model and its link to cosmology and gravity. It follows the previous Simplicity I and II workshops at Princeton University (2014) and Fermilab (2016) and will be a small informal meeting with plenty of room for discussions.

The workshops focuses on novel frontiers in observational cosmology and astrophysics and how they shed light fundamental questions in understanding the universe. Registration for this workshop is now open.

This is an ongoing series of meetings held two or three times per year between researchers at Perimeter Institute and CITA. The goal of these meetings is to share new ideas and encourage interaction in PI and CITA's common fields of interest through a series of informal talks followed by discussions.

The asymptotic safety paradigm is currently emerging as a highly promising idea for Beyond-Standard-Model physics with key progress in asymptotically safe quantum gravity and asymptotically safe matter models. The last years have seen not only the development of asymptotically safe gravity-matter models but also the discovery of asymptotically safe beyond Standard Model matter models that are under control in perturbation theory. New exciting avenues in (astro) particle physics are now waiting to be explored. For example although the nature of dark matter is a long-standing riddle it is a fact that experimental searches have so far not provided any direct clues but have instead come up with ever more stringent constraints on theoretically preferred regions of parameter space for dark-matter-models. Thus the key to unraveling this riddle could be a new theoretical paradigm to guide model builders. This workshop aims at exploring whether asymptotic safety can be a candidate for this new paradigm. We aim to bring together experts on phenomenological models and quantum gravity to probe both the theoretical viability and empirical signatures of asymptotically safe extensions of the standard model that include gravity. To facilitate a highly productive meeting that can trigger new collaborations each talk will be followed up by 15-20 minutes discussion time. Further each day of the workshop will feature a dedicated discussion session. Participants will be encouraged to contribute questions for the discussion both before as well as during the workshop. The last day of the workshop will conclude with a roadmap discussion during which all participants will be given the opportunity to propose concrete suggestions for follow-up work that might lead into future joint projects.