Cosmic string loop shapes

Understand

We analyze the shapes of cosmic string loops found in large-scale simulations of an expanding-universe string network.

• The simulation does not include gravitational back reaction, but we model that process by smoothing the loop using Lorentzian convolution.
• We find that loops at formation consist of generally straight segments separated by kinks.
• We do not see cusps or any cusp-like structure at the scale of the entire loop, although we do see very small regions of string that move with large Lorentz boosts.