ERC Consolidator 2020

Silvia Galli, Chercheuse CNRS (IAP¹)

⁽¹⁾ Institut d'Astrophysique de Paris

Projet : The New era of EUropean CMB Cosmology with the South Pole Telescope (NEUCosmoS)

Résumé (anglais) :
The goal of NEUCosmoS is to unravel some of the most severe inconsistencies that are currently threatening the so-far very successful standard model of cosmology (ΛCDM). The most critical one is the steadily growing 5σ difference in the measurement of the expansion rate of the universe today, the Hubble constant, from early-time probes (CMB) versus late-time ones (supernovae Ia). Additional discrepancies persist in the amplitude of matter perturbations, σ8, and in other fundamental parameters, such as the curvature of the universe. These anomalies, if confirmed, will have revolutionary implications for physics. In this context, NEUCosmoS will provide new, ground-breaking insight through the development of a robust analysis pipeline, allowing us to extract the most precise cosmological information from one of the forefront, post-Planck CMB experiments: the South Pole Telescope 3rd-Generation (SPT-3G). SPT-3G will measure the CMB small-scale polarization with unprecedented accuracy over the next 5 years, opening an entirely new window in CMB cosmology, with potentially original discoveries on its own. However, this statistical power will be useless without an analysis able to guarantee robustness against systematic effects, which the PI of this proposal is an expert on. For this reason, she was invited by the SPT collaboration to lead this effort, opening a unique opportunity of European access to the SPT-3G data. NEUCosmoS will provide a framework to transform the existing SPT-3G pipeline into one with quality comparable to satellite missions, building upon the PI’s Planck experience and tools, adapting them to the new challenge. The NEUCosmoS team will drive the interpretation of current and future hints of new physics in a reliable way, with statistical power comparable to the Planck satellite, and in combination with it, almost doubling the constraining capability. This will pave the way to a future contribution by Europe to the next-generation of CMB experiments.  

Matthew Morrow, Chercheur CNRS (IMJ-PRG²)

⁽²⁾ Institut de Mathématiques de Jussieu - Paris Rive Gauche

Projet :Motivic Cohomology of Schemes (MoCoS)

Résumé (anglais) :
The project belongs to the field of arithmetic algebraic geometry and is centred around algebraic K-theory, motivic cohomology, and topological cyclic homology. The overall goal is to develop a general theory of motivic cohomology for arbitrary schemes, extending the existing theory of Bloch, Levine, Suslin, Voevodsky, and others in the special case of smooth algebraic varieties. This will describe non-connective algebraic K-theory via an Atiyah--Hirzebruch spectral sequence. The project relies on very recent breakthroughs in algebraic K-theory and topological cyclic homology In the case of singular algebraic varieties, our goal will be to develop a theory of motivic cohomology which both satisfies singular analogous of the Beilinson--Lichtenbaum conjectures and is also compatible with the trace maps to negative cyclic and topological cyclic homology. Its properties will refine those of K-theory in the presence of singularities; for example, we will study a motivic refinement of Weibel's vanishing conjecture and a theory of ``infinitesimal motivic cohomology'' satisfying cdh descent. In the case of regular arithmetic schemes we will propose a new approach to the theory of p-adic motivic cohomology, based on topological cyclic homology and syntomic cohomology, which works in much greater generality than previous approaches. Perfectoid techniques will play an important role and we will establish the p-adic Beilinson--Lichtenbaum and Bloch--Kato conjectures.

Kallia Petraki, Professeure Sorbonne Université (LPTHE³)

⁽³⁾ Laboratoire de Physique Théorique et Hautes Énergies

Kalliopi Petraki travaille sur la physique des particules élémentaires au-delà du modèle standard. Elle s'intéresse à ce que les lois fondamentales de la nature peuvent nous apprendre sur l'évolution et la structure de notre univers et, inversement, à l'utilisation des observations cosmologiques et astrophysiques pour découvrir des lois de physique fondamentale inconnues. Ses recherches visent à comprendre l'origine de l'excès de matière par rapport à l'antimatière dans notre univers, ainsi que les propriétés fondamentales de la matière noire, un type inconnu de matière qui est cinq fois plus abondante que la matière ordinaire.

Projet : Charting the multi-TeV cosmos: long-range interactions in dark matter and baryogenesis (CosmoChart)

Résumé (anglais) :
The origin of the matter-antimatter asymmetry of the universe and the nature of dark matter are among the most fundamental and challenging questions in physics. Their undeniable importance has placed them in the forefront of the experimental and theoretical research in particle physics, cosmology and astrophysics. Our experimental probes are now at the outset of probing the existence of particles with the multi-TeV masses. To fully exploit the experimental effort, to design effective search strategies and correctly interpret the experimental results, we must develop reliable theoretical understanding of the plausible dynamics at this scale. The TeV scale is a new threshold. In this regime, the interactions hypothesised in a variety of well-motivated theories are mediated by lighter force carriers, and thus manifest as long-range. This is true for the most widely studied particle-physics scenario for dark matter, particles coupled to the Weak interactions of the Standard Model, as well as many other models. Moreover, many theories of matter-antimatter asymmetry generation invoke heavy particles that couple to lighter force mediators. Long-range interactions imply very different dynamics than the contact-type interactions most commonly considered in the past. They give rise to non-perturbative effects, with the most prominent being the existence of bound states. Such effects can change the experimental signatures very significantly. CosmoChart will comprehensively investigate the implications of long-range interactions along two directions:

1. The dark matter thermal decoupling in the early universe, and the radiative signals produced in the dark matter interactions inside galaxies.
2. The particle-antiparticle asymmetry generation and washout in the early universe.

Since the long-range dynamics becomes increasingly more important at higher scales, the investigations of CosmoChart will chart particle cosmology at the TeV scale and beyond.