Speaker
Description
Gravitational waves from cosmological first-order phase transitions provide a probe of physics beyond the Standard Model that complements laboratory experiments. The gravitational wave spectrum can be computed in an effective theory of a relativistic fluid coupled to a scalar field, the order parameter of the phase transition. The coupling is effected through the effective potential and the damping coefficient, from which key thermodynamic quantities can be extracted.
For transitions with moderate supercooling, the key quantities can be converted to an observable gravitational wave spectrum in a semi-analytic framework called the Sound Shell Model. We have implemented the model in the simulation library PTtools, which has been matched to numerical simulations, and extended to account for additional key physical effects. We consider selected extensions of the Standard Model, and compute the signal-to-noise ratio for the upcoming Laser Interferometer Space Antenna (LISA). These developments provide more accurate predictions of the detectability of phase transition signals at LISA, improving on the connection between the gravitational wave spectrum and the underlying particle physics.