Maxi-sizing the trilinear Higgs self-coupling: how large could it be?

Understand

In order to answer the question on how much the trilinear Higgs self-coupling could deviate from its Standard Model value in weakly coupled models, we study both theoretical and phenomenological constraints.

• As a first step, we discuss this question by modifying the Standard Model using effective operators.
• Considering constraints from vacuum stability and perturbativity, we show that only the latter can be reliably assessed in a model-independent way.
• We then focus on UV models which receive constraints from Higgs coupling measurements, electroweak precision tests, vacuum stability and perturbativity.