Gravitational waves from metastable cosmic strings in Pati-Salam model in light of new pulsar timing array data

Understand

A series of pulsar timing arrays (PTAs) recently observed gravitational waves at the nanohertz frequencies.

• Motivated by this remarkable result, we present a novel class of Pati-Salam models that give rise to a network of metastable cosmic strings, offering a plausible explanation for the observed PTA data.
• Besides, we introduce a hybrid inflationary scenario to eliminate magnetic monopoles that arise during the spontaneous symmetry breaking of the Pati-Salam gauge group to the Standard Model.
• The resulting scalar spectral index is compatible with Planck data, and the tensor-to-scalar ratio is anticipated to be extremely small.