Protonthe

Protonthe is a hypothetical elementary particle proposed in certain speculative extensions of the Standard Model of particle physics. In these frameworks, Protonthe would act as a mediator for a new short-range interaction, potentially arising from a hidden gauge symmetry. The name combines the prefix proto-, meaning first or primary, with the suffix -the, a convention referring to a theoretical particle. The term was coined in debates about physics beyond the Standard Model.

The particle is described as a possible gauge boson or composite state that couples only weakly to ordinary matter. In many models, Protonthe interacts with Standard Model particles through portal mechanisms such as kinetic mixing with photons or the Higgs portal, yielding tiny couplings to electrons, nucleons, and neutrinos. Its properties, including mass, spin, and decay channels, are model dependent. Some scenarios place Protonthe as a neutral spin-1 boson with a mass spanning from sub-eV to GeV scales; others allow scalar or higher-spin realizations. Its lifetime would typically be short if it decays to visible particles, but could be long if decays are confined to a hidden sector.

Experimental status is unsettled. No confirmed detection has emerged, but a broad program of searches—collider experiments, fixed-target and beam-dump experiments, precision measurements, and astrophysical observations—places constraints on Protonthe's parameter space. The lack of signal so far constrains certain regions while leaving others open for future exploration.

See also: dark photon, hidden sector, portal interaction, new gauge boson, millicharged particle.