6 papers
Cosmology of Gravi-Axions
Stephon Alexander, Gregory Gabadadze, Leah Jenks +1
We show how a mass term for gravitational axions (''gravi-axions'') with a Chern-Simons coupling to gravity can naturally arise due to non-perturbative contributions from Euclidean…
Beyond general relativity: gravitational waves in non-minimally coupled theories
Stephon Alexander, Tatsuya Daniel, Tucker Manton
Non-minimal couplings between matter and curvature tensors arise in many different contexts. Such couplings modify solutions of general relativity (GR) and therefore can be probed…
Detecting the -axiverse through parametric resonance
Stephon Alexander, Geoff Beck, Santiago Loane +1
Axions are a leading dark matter candidate. In this work, we study the detectability of a multi-axion-like model, dubbed the -axiverse, that is distinguishable from the string a…
Kinetically Coupled Dark Matter Condensates
Michael W. Toomey, Savvas M. Koushiappas, Stephon Alexander
Dark matter consisting of ultralight bosons can form a macroscopic Bose-Einstein condensate with distinctive observational signatures. While this possibility has been extensively s…
The Field Theory Axiverse
Stephon Alexander, Tucker Manton, Evan McDonough
Axion and axion-like particles (ALPs) are a prominent candidate for physics beyond the Standard Model, and can play an important role in cosmology, serving as dark matter or dark e…
The Kalb-Ramond field and Gravitational Parity Violation
Tucker Manton, Stephon Alexander
Gravitational wave physics can probe theories that extend beyond General Relativity. Motivated by the attention on the Kalb-Ramond field as a dark matter candidate, in this work, w…