6 papers
Can QCD Axions Survive the Cosmological Constant Problem?
Carsten van de Bruck, C. P. Burgess, Adam Smith
Mechanisms that dynamically relax the vacuum energy offer a concrete way to approach the cosmological constant problem, but because relaxation is not confined to the vacuum energy…
Multi-Field Dilaton Screening Beyond the Thin-Shell Mechanism
Philippe Brax, Carsten van de Bruck, Anne-Christine Davis +1
We analyse screening in multi-field scalar-tensor theories, focusing on systems with a dilaton coupled to matter and an axion with a dilaton-dependent kinetic term, in the presence…
The Serendipitous Axiodilaton: A Self-Consistent Recombination-Era Solution to the Hubble Tension
Adam Smith, Maria Mylova, Carsten van de Bruck +2
Axio-dilaton cosmology provides a minimal benchmark model for both Dark Matter (DM) and Dark Energy (DE) that is well motivated by fundamental physics. The axion and dilaton arise…
Dynamical Dark Energy Meets Varying Electron Mass: Implications for Phantom Crossing and the Hubble Constant
Adam Smith, Emre Ãzülker, Eleonora Di Valentino +1
We investigate the interplay between varying electron mass () and dynamical dark energy by analysing the Chevallier-Polarski-Linder (CPL) parametrization and its non-crossing…
Screened Axio-dilaton Cosmology: Novel Forms of Early Dark Energy
Adam Smith, Philippe Brax, Carsten van de Bruck +2
We study the cosmology of multi-field Dark Energy, using a well-motivated axio-dilaton model that contains the minimal number of fields to have the 2-derivative sigma-model interac…
A Minimal Axio-dilaton Dark Sector
Adam Smith, Maria Mylova, Philippe Brax +3
In scalar-tensor theories it is the two-derivative sigma-model interactions that like to compete at low energies with the two-derivative interactions of General Relativity (GR) $\u…