The discovery of the Higgs boson was a ground breaking achievement, however many of its cosmological implications are yet to be explored. In particular, it recently has become apparent that the vacuum state of the Universe is in fact not a stable one but may cataclysmically decay. Currently, this process is suppressed and for all practical purposes cannot happen, however this might not be the case for the very early stages of cosmological evolution, specifically during or immediately after the cosmic epoch known as inflation when the Universe expands at an exponential rate. All of this is directly linked to the properties of the Higgs boson, whose existence is known, however the final theory of particle physics is currently shrouded in mystery. Neutrino masses and dark matter are just a few examples that do not yet have a proper particle physics explanation, with a large number of different theoretical suggestions proposed.
A vacuum collapse of the state of the Universe during its early stages is in direct conflict with current observations, simply put, we know that the Universe has not collapsed since we are here to observe it. This way of thinking may then be used as a means of constraining physics beyond the standard model of particle physics: many novel particle physics theories designed to address some of the issues dogging the standard model may suffer from a vacuum collapse or mechanisms very similar to it in the early Universe allowing one to effectively rule them out based on the cosmological implications alone, even when their predictions would be in complete agreement with experimental results from particle accelerators.
In a nutshell, the core of this project was to push our knowledge of fundamental particle physics forward by using our understanding of cosmology. The standard model is the most tested theory science knows and so far has been remarkably successful. However, it does have its limitations and probing the vast landscape of theories designed to address these issues is the only way humanity can ever hope to discover theories that explain current observations in a more complete manner. After all, the question “why are we here?” cannot be answered without first having a complete theory of particle physics.
The main objective of this action was thus to investigate all observable consequences from the mechanisms that may lead to vacuum collapse in the early Universe in the framework of beyond standard model particle physics. Furthermore, it was also investigated whether such mechanisms could in fact the be very reason matter (dark or ordinary) exists in the first place.
