A new perspective on the electroweak phase transition in the Standard Model Effective Field Theory

• A first-order Electroweak Phase Transition (EWPT) could explain the observed baryon-antibaryon asymmetry and have a detectable gravitational wave signature, but this is not possible in the Standard Model. We therefore study the EWPT in the Standard Model Effective Field Theory (SMEFT) including dimension-six operators. A first-order EWPT has previously been shown to be possible in the SMEFT in scenarios with a tree-level barrier between minima, which requires a negative Higgs quartic coupling and a new physics scale low enough to raise questions about the validity of the EFT approach. In this work we show that a first-order EWPT is possible in a novel scenario where the barrier between minima is generated radiatively, the quartic coupling is positive, the scale of new physics is higher, and there is good agreement with experimental bounds. Our calculation is done in a consistent, gauge-invariant way, and we carefully analyze the scaling of parameters necessary to generate a barrier in the potential. We perform a global fit in the relevant parameter space and explicitly find the points with a first-order transition that agree with experimental data. We also briefly discuss the prospects for probing the allowed parameter space using di-Higgs production in colliders.

Ämnesord

NATURVETENSKAP  -- Fysik -- Subatomär fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Subatomic Physics (hsv//eng)

Nyckelord

electroweak phase transition

cosmology

effective field theory

Higgs boson

Fysik med inriktning mot elementarpartikelfysik

Physics with specialization in Elementary Particle Physics

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