359 citations · 3.8k across the 61 of their papers we have counts for
61 papers
Kinetic backreaction cannot suppress axion quantum pressure
Kaleb Anderson, Savvas M. Koushiappas
Ultralight axions from string compactifications carry non-canonical kinetic terms whose normalization is set by a coupling function that depends on an accompanying modulus field. A…
A Cosmological Uncertainty Relation and Late-Universe Acceleration
Savvas M. Koushiappas
We propose that the size of the universe and its expansion rate cannot be simultaneously specified with arbitrary precision--a quantum mechanical uncertainty encoded via a deformed…
Satellite-borne -ray astrophysics from coherent interactions in oriented crystals
Pietro Monti-Guarnieri, Gianfranco Paternò, Alexei Sytov +20
High-density and high-Z crystals are key elements of most space-borne -ray telescopes operating at gigaelectronvolt energies (such as Fermi-LAT). The lattice structure is usuall…
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…
Field Equations in Chern-Simons-Gauss-Bonnet Gravity
Alexis Ortega, Tatsuya Daniel, Savvas M. Koushiappas
We investigate the effects of Chern-Simons-Gauss-Bonnet gravity on fundamental metrics. This theory involves perturbative corrections to general relativity, as well as two scalar f…
Quantum Gravity Signatures in the Late-Universe
Michael W. Toomey, Savvas Koushiappas, Bruno Alexandre +1
We calculate deviations in cosmological observables as a function of parameters in a class of connection-based models of quantum gravity. In this theory non-trivial modifications t…