November 11: Andrew Long (ASU)

Title: Particle Production from Cosmic Strings
Time: 1pm
Place: 4N9
 
Abstract: Cosmic strings form when an Abelian symmetry is spontaneously broken. How can we determine if the universe is permeated by a network of cosmic strings, and what would it teach us about physics beyond the Standard Model? If the symmetry breaking scale is high (say GUT scale), then the strings are so massive that they should have been detected through lensing of the cosmic microwave background. Lighter strings cannot be exposed by gravitational probes, and we must look for evidence of them through their particle emission. For instance, radiation from the string may induce an electromagnetic cascade that is detected on Earth in the form of a diffuse gamma ray flux. I will discuss cosmic strings in a generic “hidden sector” extension of the Standard Model, which has often been studied in the context of dark matter, collider phenomenology, and electroweak baryogenesis. The Standard Model fields couple to the cosmic string, and I’ll show how this leads to particle production, and I’ll also discuss the associated cosmological and astrophysical signatures.