8 papers
More Axions from Strings
Marco Gorghetto, Edward Hardy, Giovanni Villadoro
We study the contribution to the QCD axion dark matter abundance that is produced by string defects during the so-called scaling regime. Clear evidence of scaling violations is fou…
Exploring Hamiltonian Truncation in
Joan Elias Miro, Edward Hardy
We initiate the application of Hamiltonian Truncation methods to solve strongly coupled QFTs in . By analysing perturbation theory with a Hamiltonian Truncation regulator, w…
Thermal Dark Energy
Edward Hardy, Susha Parameswaran
We present a novel source of dark energy, which is motivated by the prevalence of hidden sectors in string theory models and is consistent with all of the proposed swampland conjec…
Hearing without seeing: gravitational waves from hot and cold hidden sectors
Malcolm Fairbairn, Edward Hardy, Alastair Wickens
We study the spectrum of gravitational waves produced by a first order phase transition in a hidden sector that is colder than the visible sector. In this scenario, bubbles of the…
Axions from Strings: the Attractive Solution
Marco Gorghetto, Edward Hardy, Giovanni Villadoro
We study the system of axion strings that forms in the early Universe if the Peccei-Quinn symmetry is restored after inflation. Using numerical simulations, we establish the existe…
Higgs portal dark matter in non-thermal cosmologies
Edward Hardy
A scalar particle with a relic density set by annihilations through a Higgs portal operator is a simple and minimal possibility for dark matter. However, assuming a thermal cosmolo…