Cosmic microwave anisotropies from BPS semilocal strings

Understand

We present the first ever calculation of cosmic microwave background CMB anisotropy power spectra from semilocal cosmic strings, obtained via simulations of a classical field theory.

• Semilocal strings are a type of non-topological defect arising in some models of inflation motivated by fundamental physics, and are thought to relax the constraints on the symmetry breaking scale as compared to models with (topological) cosmic strings.
• We derive constraints on the model parameters, including the string tension parameter mu, from fits to cosmological data, and find that in this regard BPS semilocal strings resemble global textures more than topological strings.
• The observed microwave anisotropy at l = 10 is reproduced if Gmu = 5.3x10^{-6} (G is Newton's constant).