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From Fermi to Planck : a bottom up approach

Periodic Reporting for period 4 - NuBSM (From Fermi to Planck : a bottom up approach)

Reporting period: 2021-04-01 to 2022-03-31

The theory of elementary particles and their interaction is so hugely successful that it has been dubbed "Standard Model" of particle physics. It has been tested in experiments at ever increasing energies, culminating in the recent discovery of the Higgs boson and describes all the accelerator observed phenomena with impressive precision. Nevertheless, some major riddles cannot be addressed by the Standard Model, such as neutrino oscillations, the existence of Dark Matter, the absence of primordial antimatter in the Universe. New fundamental principles, interactions and unknown yet particles are required to address these questions. No evidence for new physics has been found so far at the Large Hadron Collider and previous accelerator experiments. This means that the new particles are either heavier than the reach of modern accelerators or that they are sufficiently light but interact too feebly with known matter to be detected. In the latter case new particles should be searched at Intensity Frontier experiments.

The overall objective of this project is to explore and develop an alternative idea that the resolution of the "beyond-the-Standard-Model" problems can be provided by extremely feebly interacting particles (weaker-than-neutrino) with masses as light as other known particles. Along the same lines we also explore the possibility that cosmological inflation does not require a new field, but is driven by the Higgs field of the Standard Model.

Importance: The proposed model, if correct, will successfully blend the Standrad Model of particle physics and the "cosmological concordance model" into a common theory of particle physics AND cosmology (i.e. of micro and macro scales). Thus we will have a complete microscopical description of the Universe, that we can literally put into the supercomputers and reconstruct the whole observed Universe starting with simple initial conditions.

Main Objectives of the project include:
A: To establish a quantitative relation between the primordial properties of dark matter particles and the parameters of heavier sterile neutrinos to be searched for at accelerators --- the objectives allows to build a cosmic connections of the proposed theory.

B: To pin down the parameter space for future accelerator searches by using all available cosmological and astrophysical data and deriving new constraints on the possible primordial properties of dark matter particles -- with new generation of experiments being planned for mid-2020s it is important to deliver our best expectations.

C: To study possible high-energy completions of the Standard Model with gravity that assume no new particles
from Fermi to quantum gravity scales --- an objective that would address the most fundamental questions of particle physics: "Why some numbers are small? What are most fundamental symmetries of nature?"
We advanced greatly along all 3 objectives:
- theoretical computations of how the primordial plasma evolved and particle-antiparticle asymmetry appeared
- theoretical works and numerical studies of chiral plasma evolution and the rates of microscopical processes that drive the chiral asymmetry evolution
- Astronomical data analysis in order to explore the nature of 3.5 keV line
- Cosmological data analysis and novel ways to use Lyman-alpha forest method to explore primordial properties of dark matter particles
- Theoretical investigations of quantum scale invariance
We are expecting that our new methodology and efforts put into the Lyman-alpha forest method will give a definitive answer regarding the presence of dark substructures. On top of that we are hoping to measure dark substructures directly with the gravitational lensing.

We expect to explore the potential of SHiP and other intensity frontier experiments towards the searches for heavy neutral leptons and to provide experimentalists with the "focus points" for HNL searches

We are optimistic about developing the full quantum scale invariant theory that