Gravitational waves and proton decay: complementary windows into GUTs

Understand

Proton decay is a smoking gun signature of Grand Unified Theories (GUTs).

• Searches by Super-Kamiokande have resulted in stringent limits on the GUT symmetry breaking scale.
• The large-scale multipurpose neutrino experiments DUNE, Hyper-Kamiokande and JUNO will either discover proton decay or further push the symmetry breaking scale above $10^{16}$ GeV.
• Another possible observational consequence of GUTs is the formation of a cosmic string network produced during the breaking of the GUT to the Standard Model gauge group.