Protoneres

Protoneres are a proposed family of short-lived resonant states linked to the proton. In certain theoretical discussions of hadron spectroscopy, protoneres are excited configurations of the proton’s internal quark-gluon field that exist briefly before decaying. They are distinguished from the ground-state proton by higher mass and different quantum numbers; their properties depend on the specific model and assumptions about strong-interaction dynamics.

Characteristics commonly considered include a range of masses above the proton, various spin and parity assignments, and decay channels that favor proton plus one or more mesons (for example a proton plus pions) or neutron plus mesons. The inferred lifetimes are extremely short, on the order of 10^-23 to 10^-22 seconds, making direct observation challenging. The precise spectrum of protoneres is model-dependent and not universally agreed.

Experimental status: Searches in high-energy hadron collisions and lepton-hadron scattering have yielded hints in some analyses but have not produced a consensus or confirmed discovery. Constraints from scattering data place limits on possible production rates and decay modes, and many claimed signals are debated or attributed to conventional nucleon resonances or kinematic effects. As such, protoneres remain a speculative concept in contemporary hadron physics.