Singling out SO(10) GUT models using recent PTA results
Stefan Antusch, Kevin Hinze, Shaikh Saad, Jonathan Steiner
Abstract
In this work, we construct promising model-building routes towards SO(10) grand unified theory inflation and examine their ability to explain the recent pulsar timing arrays (PTAs) results hinting at a stochastic gravitational wave (GW) background at nanohertz frequencies. We consider a supersymmetric framework within which the so-called doublet-triplet splitting problem is solved without introducing fine-tuning. Additionally, realistic fermion masses and mixings, gauge coupling unification, and cosmic inflation are incorporated by utilizing superfields with representations no higher than the adjoint representation. Among the three possible scenarios, two of these cases require a single adjoint Higgs field, and do not lead to cosmic strings. In contrast, the third scenario featuring two adjoints, can lead to a network of metastable cosmic strings that generates a GW background contribution compatible with the recent PTA findings and testable by various ongoing and upcoming GW observatories.