leptonantal

Leptonantal is a term used in speculative physics and science-fiction-inspired models to denote a neutral bound state formed by a lepton and its antiparticle. In several beyond-the-Standard-Model scenarios, the constituents are held together by a short-range interaction distinct from the ordinary electromagnetic force, sometimes described as a lepton-specific mediator or a portal to a hidden sector. The concept is analogous to quarkonium, but realized in the lepton sector with leptons such as electrons or muons acting as the building blocks. Leptonantals would be distinct from ordinary bound states like positronium by the assumed properties of the binding force and mediator.

Properties proposed for leptonantals include neutrality and the possibility of different spin configurations, such as singlet or triplet states. Their masses would be close to twice the constituent lepton mass, corrected by a small binding energy. Lifetimes depend on the annihilation rate into photons, neutrinos, or lighter leptons, and in many models are predicted to be very short, though some variants allow longer lifetimes if certain decays are suppressed by selection rules. Decay channels and production mechanisms are model-dependent, but commonly discussed channels include diphoton or dilepton final states and, in some scenarios, hidden-sector final states.

Theoretical context positions leptonantals as hypothetical probes of lepton-number structure and potential connections to dark sectors through mediator particles such as dark photons or scalar portals. They remain speculative and have no experimental confirmation within the Standard Model framework. If discovered, leptonantals would offer insights into lepton flavor dynamics, new binding forces, and possible links between visible matter and hidden sectors.

See also positronium, true muonium, quarkonium, dark photon.