Theoretical uncertainties for cosmological first-order phase transitions

We critically examine the magnitude of theoretical uncertainties in perturbative calculations of fist-order phase transitions, using the Standard Model effective field theory as our guide. In the usual daisy-resummed approach, we find large uncertainties due to renormalisation scale dependence, which amount to two to three orders-of-magnitude uncertainty in the peak gravitational wave amplitude, relevant to experiments such as LISA. Alternatively, utilising dimensional reduction in a more sophisticated perturbative approach drastically reduces this scale dependence, pushing it to higher orders. Further, this approach resolves other thorny problems with daisy resummation: it is gauge invariant which is explicitly demonstrated for the Standard Model, and avoids an uncontrolled derivative expansion in the bubble nucleation rate.

Automated summary

This study critically examines the magnitude of theoretical uncertainties in perturbative calculations of fist-order phase transitions. It finds that using a more sophisticated perturbative approach with dimensional reduction drastically reduces the scale dependence and resolves other problems with daisy resummation.