Basically, they are hypothetical particles that have been added to the standard model to propose solutions to many unsolved problems in physics. The particles are interesting because there is no actual new physics involved with them, and they can be easily proven or disproven with testing
CrispCrisp t1_irpvb2r wrote
Reply to What are SMASH(Standard Model Axion Seesaw Higgs) particles? by Actual-ActualStudioZ
Basically, they are hypothetical particles that have been added to the standard model to propose solutions to many unsolved problems in physics. The particles are interesting because there is no actual new physics involved with them, and they can be easily proven or disproven with testing