Charting the multi-TeV cosmos: long-range interactions in dark matter and baryogenesis

Project Information

CosmoChart

Grant agreement ID: 101002846

DOI

10.3030/101002846

EC signature date 23 February 2021

Start date 1 September 2021

End date 31 August 2027

Funded under

• EXCELLENT SCIENCE - European Research Council (ERC)

Total cost

€ 1 998 437,00

EU contribution

€ 1 998 437,00

Coordinated by

SORBONNE UNIVERSITE
France

Periodic Reporting for period 3 - CosmoChart (Charting the multi-TeV cosmos: long-range interactions in dark matter and baryogenesis)

Reporting period: 2024-09-01 to 2026-02-28

Summary of the context and overall objectives of the project

The origin of matter is one of the most fundamental and challenging problems in science. Cosmological and astrophysical observations have revealed that ordinary matter makes up only about 5% of the energy density of our universe, while 25% is in the form of some yet unknown particles that do not interact electromagnetically (or do so very weakly), referred to as dark matter. Dark matter has so far manifested only gravitationally. While its existence is essential in understanding the universe as we observe it, the particle species it consists of and their non-gravitational interactions remain unknown. And even though the properties of ordinary matter are largely known, the origin of its cosmological abundance - consisting mostly of protons and neutrons, collectively called baryons - is still shrouded by mystery. While it is known that it is due to an excess of baryons over antibaryons (also called an asymmetry), the dynamical generation of this excess in the early universe requires physics beyond the what is currently known.

The project CosmoChart concerns the origin of the cosmological abundance of ordinary matter and dark matter, and the fundamental nature of the latter. Elucidating these issues will not only allow us to understand the evolution and the structure of our universe better, but will also constitute a momentous discovery of new fundamental physics. The overall objectives include building theories for the generation of the ordinary matter-antimatter asymmetry and for dark matter, and examining their theoretical and phenomenological implications, such that these theories can be tested by our experimental probes.

The project is contributing to our understanding of the universe and the most fundamental laws of nature. The importance of this endeavour cannot be overemphasised. The comprehension of the physical world, and the dissemination of the knowledge to the society, liberated our societies from fears and superstitions, enabled us to solve big problems and build prosperous and creative societies. Fundamental research has also more immediate impact. The contributions of the field of high-energy physics to the technological advancement of our entire society are well-known and wide-ranging, from inventing the world wide web, to advancing medical technology. Theoretical research, such as that carried out in this project, is an integral part of the research, and indeed of any discovery in particle physics. It provides the vision and the essential guidance that enable us to design effective experimental strategies which can lead to important discoveries.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Since its start, the CosmoChart team has worked on a variety of scenarios for dark matter and baryogenesis, as well as other aspects of physics beyond the Standard Model. The main studies and results include the following:

1) Developed the formalism for the dark matter decoupling in early universe when metastable dark matter bound states exist in the spectrum of the theory.
2) Investigated the effect of dark matter semi-annihilation with right-handed neutrinos, on the dark matter relic density and indirect detection signals.
3) Derived constraints on the interaction strength between dark matter and electrons, taking into account that the scattering of dark matter particles on electrons in the galaxy can accelerate dark matter particles thus enhancing their recoil in direct detection experiments.
4) Derived exclusion limits on dark matter-neutrino scattering cross-section.
5) Proposed an explanation for an anomaly appearing in flavour experiments (RKstar) in the context of R-partity violating supersymmetry.
6) Proposed an explanation for the excess observed at the dark matter direct detection experiment Xenon1T, using an extended scalar sector.
7) Put forward a scenario where the matter-antimatter asymmetry generation in the early universe leads also to the formation of primordial black holes that contribute to dark matter, and showed that this scenario may have led to the production of gravitational waves in the early universe.
8) Proposed a minimal scenario of electroweak symmetry non-restoration at high temperatures in the early universe.
9) Investigated how angular correlations in nuclear beta decay are important tests of the Standard Model.
10) Employed gamma-ray observations by H.E.S.S. to place constraints on dark matter annihilation.
11) Investigated many technical aspects of phase transitions in the early universe.
12) Explored the possibility of magnetic field generation in the early universe from phase transitions, that acted as seeds for the large scale magnetic fields today.
13) Calculated the gravitational production of particles whose decay could subsequently generate the matter-antimatter asymmetry of the universe.
14) Developed a complete and unique framework for unitarizing inelasting scattering via resummation of the contributions of inelastic processes to the self-energy of the incoming state
15) Applied the method to contact interactions that need renormalization, and to ultra-soft processes (bound-state formation) that exhibit rich non-analytic structure in the complex momentum plane.
16) Examined the phenomenological implications of the aforementioned unitarization scheme for dark-matter freeze-out, by applying it to bound-state formation processes
17) Proposed a new type of inelastic scatterings that exhibit critical and supercritical behaviour, in the context of leptogenesis and baryogenesis
18) Investigated the effect of density inhomogeneities on leptogenesis

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The expected investigations until the end of the project include:
1) Non-perturbative effects due to long-range interactions in the context of matter-antimatter asymmetry generation.
2) The effect of the Higgs doublet as a light force mediator in the context of dark matter and baryogenesis.
3) Resummation of inelastic interactions to compute the effective potential, and application to phase transitions in the early universe.
4) The effect of unitarization on the dark matter elastic self-scattering