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Each year an eminent theoretical physicist holds the Lorentz Chair. The 2017 Lorentz professor is Renata Kallosh, from Stanford University. Her stay in Leiden will overlap with the visit of professor Andrei Linde, and they will jointly organize the Lorentz Center workshop on Theoretical Approaches to Cosmic Acceleration (3-7 July, 2017). In addition, Prof Lallosh will present a Colloquium Ehrenfestii on Wednesday evening June 14. The Professors Kallosh and Linde will give three joint lectures starting on June 15, 'From Cosmological Observations to Fundamental Physics'.

Joint lectures by Prof Kallosh and Prof Linde

From Cosmological Observations to Fundamental Physics 
June 15, 22, and 26 (13:45-15.30). 

According to the cosmological observations during the last two decades, 70% of matter of the universe is in a vacuum-like state with positive energy density. This vacuum-like state is similar to the state of matter required for the exponential expansion of the universe in inflationary cosmology. Historically, it was difficult to describe positive vacuum energy (cosmological constant) in supergravity and string theory, but in the last 15 years new tools have been developed to address this issue. Similar tools, based on string theory and a non-linear realization of supersymmetry, also help with constructing realistic inflationary models. New observations confirmed the basic predictions of inflation: flat geometry, Gaussian inflationary fluctuations with a nearly flat spectrum. The Holy Grail of observational cosmology is a detection of primordial gravitational waves, B-modes in the CMB polarization. Our goal is to develop inflationary models in string theory/supergravity, which can successfully describe new observational data. We will discuss a general class of inflationary models which are compatible with all presently available data. These include the alpha-attractor models based on the hyperbolic geometry of the internal space. They provide specific B-mode targets for the future CMB Stage-4 and satellite missions, such as LiteBird, Pixie, and CORE. These new experiments could potentially probe fundamental physics, including quantum gravity, at energies up to 10^13 GeV. The theoretical developments in this area may shed new light not only on particle interactions at extremely large energies, but also on the origin of the universe and its global structure.

  • Thursday June 15: Inflationary cosmology
  • Thursday June 22: De Sitter vacua in string theory and supergravity
  • Monday June 26: Alpha-attractor models and B-mode targets

Location: De Sitterzaal, Oortgebouw, Niels Bohrweg 2, Leiden

Colloquium Ehrenfesti

On Wednesday 14 June, Prof. Renata Kallosh will give the Leiden Ehrenfest Colloquium, From Planck to Escher.

The recent observations of the Cosmic Microwave Background by the Planck satellite strongly support the standard cosmological model, defined by just a few independent parameters. Two of them in particular still require a theoretical explanation: the small deviation from scale invariance in the power spectrum of the initial density fluctuations, and the level of inflationary gravitational waves, detectable through B-mode polarization in the CMB. Following an introduction to inflationary cosmology, I will describe a recently developed class of inflationary models, motivated by maximal supersymmetry and string theory, that gives specific targets for future B-mode experiments. These models are based on the hyperbolic geometry of the Poincare disk, which is beautifully represented by Escher's picture Circle Limit IV. The Colloquium will start at Wednesday 14 June, 19:30 hours in the main auditorium of the Oort building, Niels Bohrweg 2 Leiden. 

Workshop Theoretical Approaches to Cosmic Acceleration, 3 - 7 July 2017

Connecting String, Supergravity and Quantum Field Theory Aspects of (Near-) De Sitter Space 

Scientific organisers: 

Ana AchĂșcarro (Leiden, The Netherlands)   
Renata Kallosh (Stanford, CA, USA)   
Andrei Linde (Stanford, CA, USA)   
Diederik Roest (Groningen, The Netherlands)   
Jan Pieter van der Schaar (Amsterdam, The Netherlands)   
Koenraad Schalm (Leiden, The Netherlands)  

More information and registration on the website of the Lorentz Center