#### New cosmological concordance with massive sterile neutrinos?

- Event time: 2:00pm
- Event date: 7th May 2014
- Speaker: Hiranya Peiris (University College London)
- Location: Higgs Centre Seminar Room, James Clerk Maxwell Building (JCMB) James Clerk Maxwell Building Peter Guthrie Tait Road Edinburgh EH9 3FD GB

### Event details

It has been claimed recently that massive sterile neutrinos could bring about a new concordance between observations of the cosmic microwave background (CMB), the large-scale structure (LSS) of the Universe, and local measurements of the Hubble constant, H0. I will demonstrate that this apparent concordance results from combining datasets which are in significant tension, even within this extended model, possibly indicating remaining systematic biases in the measurements. I will further show that this tension remains when the cosmological model is further extended to include significant tensor modes, as suggested by the recent BICEP2 results. Using robust data combinations, I will present stringent limits for the sum of active and sterile neutrinos, respectively. A pedagogical introduction will be provided for the cosmological signatures of extensions to the neutrino sector of the Standard Model of particle physics.

The Particle Physics Theory seminar is a weekly series of talks reflecting the diverse interests of the group. Topics include analytic and numerical calculations based on the Standard Model of elementary particle physics, theories exploring new physics, as well as more formal developments in gauge theories and gravity..