The team has named their new model SMASH for “Standard Model Axion See-saw Higgs portal inflation.” The proposed particles are rho (to help explain inflation), the axion (to help explain dark matter) a color triplet fermion and three heavy right-handed neutrinos.
In their paper published in the journal Physical Review Letters, Guillermo Ballesteros with Université Paris Saclay, Javier Redondo with Universidad de Zaragoza, Andreas Ringwald with Max-Planck-Institut für Physik and Carlos Tamarit with Durham University describe the six particles they would like to add and why.
The standard theory is, of course, a model that has been developed over the past half-century by physicists to describe how the universe works, and includes such things as the electromagnetic, strong and weak interactions, and also describes what are believed to be the particles that play a role in it all. To date, the theory lists 17 fundamental particles and has stood up against rigorous testing, but it still does not include explanations for what are considered to be some fundamental things.
They have assembled what they believe are the most promising theories regarding several problems with the standard model and their possible solutions, and have put them together as an outline of sorts for research moving forward.
It is still far too early to predict whether the model will be accepted by the physics community, but one thing it has in its favor is that the predictions it makes are clear, which means they can be tested and either proved or disproved. It should be noted that the theory does not include such things as the hierarchy problem or deal with the cosmological constant.