12:00–1:00 pm ERC 401
Fabrizio Rompineve (CERN) "Spontaneously broken discrete symmetries are a common ingredient of beyond the Standard Model physics"
In this talk, we discuss how the resulting potentially dangerous domain walls can be used as a cosmic laboratory to probe the quality of global symmetries. Symmetry breaking terms can indeed cause annihilation of the network. This violent phenomenon generates a stochastic gravitational wave (GW) background, which can be searched for at current and future GW observatories. We first present the sensitivity of interferometers to heavy QCD axion models, in which the axion potential receives an aligned contribution from a heavy sector. We show that these scenarios can have GW signatures correlated with measurable neutron (and proton) Electric Dipole Moments. We then present the first dedicated search for GWs from annihilating domain walls in the latest Pulsar Timing Array datasets. We show that the common process spectrum recently detected by PTAs can provide the first observational hints of domain walls annihilating slightly below the QCD phase transition. We discuss how these can arise from heavy axion models, with correlated signatures at CMB or collider and laboratory experiments.