Theoretical Uncertainties in First-Order Electroweak Phase Transitions

Abstract: We systematically investigate theoretical uncertainties in perturbative analyses of first-order electroweak phase transitions (EWPT). Utilizing the Standard Model Effective Field Theory (SMEFT) framework, we quantify the gauge dependence, renormalization scheme, and scale dependences in predicting phase-transition parameters across both zero and finite chemical potential regimes. Our key findings reveal that: 1) the gauge-parameter dependence and the chemical potential are subdominants, and 2) Baryon number preservation criteria and phase transition observables exhibit pronounced sensitivity to the renormalization scale in the ${\overline{\rm MS}}$ scheme. Comparative analyses with the on-shell scheme demonstrate that within strongly first-order EWPT parameter spaces, the ${\overline{\rm MS}}$ scheme predicts enhanced phase transition strengths and prolonged transition durations.