26–30 May 2025
Centro Culturale Altinate San Gaetano
Europe/Rome timezone

Explaining the PTA signal and dark matter with a conformal dark sector

28 May 2025, 15:00
20m
Spazio 35 (Centro Culturale Altinate San Gaetano)

Spazio 35

Centro Culturale Altinate San Gaetano

Via Altinate 71, Padova

Speaker

Carlo Tasillo (Uppsala University)

Description

Strong first-order phase transitions offer a compelling explanation for the stochastic gravitational wave background in the nano-Hertz range measured by pulsar timing arrays (PTA). In this talk, I will consider a classically conformal dark sector in which the breaking of a dark U(1) gauge symmetry gives rise to a gravitational wave background that can fit the PTA data and additionally sources the mass of a stable fermionic sub-GeV dark matter candidate. The model is coupled to the Standard Model via a dark photon mediator which is tightly constrained by laboratory searches. I will discuss these accelerator constraints as well as cosmological constraints coming from the decay of dark Higgs bosons after the phase transition. Finally, I will present the results of a global fit and show that the model has viable parameter space where it fits the PTA data, reproduces the observed relic abundance and avoids all relevant constraints.

Author

Carlo Tasillo (Uppsala University)

Co-authors

Prof. Felix Kahlhoefer (KIT) Jonas Matuszak (KIT) Sowmiya Balan (KIT) Prof. Torsten Bringmann (Oslo University)

Presentation materials