Physics Theory Seminar with Fazlollah Hajkarim on “A Precise Fitting Formula for Gravitational Wave Spectra from Phase Transitions”

We present a more precise fit function for predicting the gravitational wave (GW) spectrum from phase transitions, crucial for beyond Standard Model (BSM) physics. The widely used single broken power law fit often misses key features of the GW spectrum. Our approach introduces a double broken power law, accounting for both inter-bubble spacing and sound shell thickness, providing a more accurate spectrum based on the sound shell model. Through detailed scans of thermodynamic parameters, including phase transition strength and bubble wall velocity, we demonstrate that our fit function better captures the GW spectrum across various BSM scenarios. This refined fit can generate accurate GW spectra using inputs like phase transition strength, bubble wall velocity, nucleation rate, and nucleation temperature.

This lecture was made possible by the William C. Ferguson fund.