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v3.3.3
Speaker: Thomas Steingasser
Title: Higgs criticality in and beyond the Standard Model
Abstract: Both parameters in the Higgs field's potential, its mass and quartic coupling, appear fine-tuned to near-critical values, which gives rise to the hierarchy problem and the metastability of the electroweak vacuum. Whereas such behavior appears puzzling in the context of particle physics, it is a common feature of dynamical systems, which has led to the suggestion that the parameters of the Higgs potential could be set through some dynamical process. In my talk, I will discuss how this notion could be extended to physics beyond the Standard Model.
I will first explain what it means for the parameters of the Higgs potential to be “critical”, with a particular focus on the fact that there exist, a priori, multiple realizations of this notion. I will then discuss some results which indicate that some of the tunings necessary to achieve criticality are, in fact, not independent. (See, e.g., [2108.09315].) Furthermore, I will explain a simple technique that allows to efficiently identify critical sets of parameters, in many cases allowing for analytical results.
In the second half of my talk, I will present a recent conjecture suggesting that, whatever mechanism is ultimately responsible for the criticality of the Higgs, also affects related BSM physics. Most importantly, I will argue that this allows for concrete, measurable predictions, which are, in the best case, independent of the concrete mechanism causing criticality. I will first illustrate this for the case that the scale of new physics lies beyond the so-called instability scale, which allows for an efficient EFT treatment. (See, e.g., [2307.10361].) This scenario can potentially be checked through cosmological observations, for which I will provide some first, tentative results. Lastly, I will talk about ongoing work to extend our approach to scenarios with new physics below the instability scale.