Dear all,

after the discussions in the last Einstein Toolkit workshop in Mallorca we have formed a new working group "Cosmology and Particles" led by Eloisa and myself. This group will serve as arena to discuss extensions of numerical relativity towards new physical applications in cosmology (e.g. modelling inflation, structure formation or the interplay between compact objects and dark matter candidates) and high-energy physics, and their implementation in the Einstein Toolkit.