SEARCHING FOR SCALAR DARK MATTER USING SIX YEARS OF LNE-SYRTE FOUNTAIN CLOCK COMPARISON DATA

A. Hees (1) , J. Guena (1) , M. Abgrall (1) , S. Bize (1) , P. Wolf (1)

1 SYRTE - Systèmes de Référence Temps Espace

We use six years of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine-structure constant, and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed. While thoroughly tested 1 , the theory of General Relativity (GR) is currently challenged by theoretical considerations and by galactic and cosmological observations. Indeed, the development of a quantum theory of gravitation or of a theory that would unify gravitation with the other fundamental interactions leads to deviations from GR. These modifications are usually characterized by the introduction of new fields in addition to the space-time metric to model the gravitational interaction. For example, string theory generically predicts the existence of new scalar fields. In addition, in the current cosmological paradigm, some galactic and cosmological observations are explained by the introduction of cold Dark Matter (DM) and of Dark Energy. Little is currently known about these two components that constitute the major part of our Universe. They can be interpreted as new types of matter (although not directly detected so far), as a modification of the gravitational theory or as a combination of the two. The introduction of non minimally coupled scalar fields additionally to GR (tensor-scalar theories) generally leads to a space- time dependence of fundamental constants, which can then be searched for by experiments that test the Einstein equivalence principle (EEP) like weak equivalence principle (WEP) tests or tests of local position or Lorentz invariance (LPI and LLI) 1. Such scalar fields could be a candidate for DM and/or dark energy. In several scenarios, a massive scalar field will oscillate at a frequency related to its mass, leading to a corresponding oscillation of fundamental constants 2,3. Recently atomic spectroscopy of Dy has been used to constrain such oscillations 4 of the fine structure constant (α). In this proceeding, we present limits on possible oscillations of a linear combination of constants (α, quark mass and Λ quantum chromodynamics – QCD – mass scale) using six years of highly accurate hyperfine frequency comparison of Rb and Cs atoms 5. This provides complementary constraints to those from Dy spectroscopy 4 which is sensitive to α alone. When assuming a variation of α only, our results improve the limits of Van Tilburg et al 4 by over an order of magnitude.

Mots clés: experimental equipment; experimental methods; experimental results; data analysis method; field theory: scalar; fundamental constant: fine structure; dark matter: scalar; mass: scale; coupling: scalar; gravitation: interaction; fermion: mass; quark: mass; transition: frequency; gravitation: model; invariance: Lorentz; equivalence principle; quantum chromodynamics; dark energy; rubidium; galaxy: halo; general relativity; oscillation; time dependence; space-time; duality; string model

Domaines: Astrophysique [astro-ph]

A. Hees, J. Guena, M. Abgrall, S. Bize, P. Wolf. SEARCHING FOR SCALAR DARK MATTER USING SIX YEARS OF LNE-SYRTE FOUNTAIN CLOCK COMPARISON DATA. 52nd Rencontres de Moriond on Gravitation, Mar 2017, La Thuile, Italy. pp.165-168. ⟨hal-01802017⟩