An extended scalar sector often emerges in models motivated by the electroweak hierarchy problem. In particular, a SM triplet is interesting because its decay is very constrained at the renormalizable level. Therefore, effective operators with a low cutoff make the triplet components decay promptly.
I'll discuss the role of the Higgs boson as a probe of the hidden sector. The latter is of particular importance in cosmology as it may host dark matter and the inflaton. Due to its scalar nature, the Higgs boson provides a unique handle on properties of such Standard Model--singlet states.
Gr@v warmly congratulates the Event Horizon Telescope collaboration for the first direct image of a black hole. This discovery has had a worldwide impact, including news coverage in Portugal with the contribution of Gr@v and former Gr@v members.
Axions can play very important roles in cosmology. They are interesting candidates for dark matter, dark energy, inflation but also, in the case of the QCD axion, a natural solution to the strong CP problem.
In a recent paper "Spontaneous scalarisation of charged black holes: coupling dependence and dynamical features", [arXiv:1902.05079], by Gr@v members A. Pombo and E. Radu, in collaboration with a group at IST-Lisbon (P. Fernandes, C. Herdeiro and N. Sanchis-Gual), fully non-linear evolutions of the process of spontaneous scalarisation of charged black holes.
Gr@v member Valério Ribeiro was part of an international team of researchers studying thermonuclear eruptions in the Andromeda galaxy. The team published, in Nature magazine, the discovery of a super-nova remnant which is bigger than most supernova remnants. They found that the super-nova remnant was the consequence of yearly repeated eruptions over millions of years. Few of these systems are known in the galaxy due to the fact that we suffer from dust obscuration.
The Two Higgs Doublet Model (2HDM) is an excellent candidate for physics
Beyond the Standard Model, and it predicts the existence of extra scalar particles
liable to be discovered in the coming years at the LHC. Unlike the Standard Model,
however, the 2HDM scalar potential has a rich vacuum structure, with
competing minima possible already at tree-level.
I will explore the idea of connecting the dark matter sector with a sector of the Standard Model (SM), namely the neutrino sector. To do this, I consider the extension of the SM with right-handed (gauge singlet) neutrinos, which will lead to a type-I seesaw mechanism. Then I also add a fermion (another gauge singlet) dark matter candidate.
Our group coordinated the "Numerical Relativity and High Energy Physics" IRSES network (2012-2015). Here is a list of the global network meetings organized:
