Tegenions

Tegenions are hypothetical elementary particles proposed in certain beyond-Standard-Model theories that extend the particle content with a new gauge sector. The term is used in some theoretical discussions to describe fermionic or bosonic states that interact with standard matter through a limited set of portal couplings. They are often explored as candidates for dark matter or as mediators of a new fundamental force.

In typical formulations, tegenions are electrically neutral and can be Dirac or Majorana fermions (or corresponding bosons) with masses spanning many orders of magnitude, from keV to TeV scales. Some models impose a stabilizing symmetry, ensuring long lifetimes on cosmological timescales. Their self-interaction strength and abundance depend on the underlying model.

Interactions with ordinary matter are intentionally weak and mediated via portal interactions, such as a Higgs portal, a kinetically mixed U(1) gauge boson, or neutrino-like couplings. Because of these portals, tegenions can be produced in high-energy collisions and in the early universe, though their signals are challenging to distinguish from backgrounds.

Cosmologically, tegenions are studied as potential dark matter candidates or as components of early-universe dynamics. Observational constraints come from the cosmic microwave background, big bang nucleosynthesis, large-scale structure, and direct detection experiments. Collider searches look for missing energy signatures or resonance structures associated with the new gauge sector.

As of now, tegenions remain theoretical and speculative; no experimental confirmation has been reported. They serve as a framework for exploring how a hidden sector might couple to the Standard Model and for testing ideas about dark matter and new forces.