Gravitational Waves from Global Second Order Phase Transitions
  Global second-order phase transitions are expected to produce scale-invariant
gravitational wave spectra. In this manuscript we explore the dynamics of a
symmetry-breaking phase transition using lattice simulations. We explicitly
calculate the stochastic gravitational wave background produced during the
transition and subsequent self-ordering phase. We comment on this signal as it
compares to the scale-invariant spectrum produced during inflation.
