twobaryon

Twobaryon is a term used in hadron and nuclear physics to denote a system composed of two baryons, that is, a hadronic state with baryon number B=2. Such systems can be bound, forming a dibaryon, or exist as resonances in baryon–baryon interactions. The deuteron, a bound state of a proton and a neutron, is the best-known and the only established two-baryon bound state in nature. It has isospin I=0, total angular momentum J^P=1^+, and a binding energy of about 2.224 MeV. Other two-baryon configurations, such as two neutrons or two protons in free space, are not bound by the strong interaction, though they can appear in larger nuclei or as transient states in scattering.

Theoretical interest extends to dibaryon candidates predicted by quantum chromodynamics (QCD) inspired models, including the H-dibaryon (uuddss) proposed by Jaffe, as well as other multi-strangeness or resonance-like configurations. Lattice QCD and effective field theory approaches have explored whether attractive forces in particular two-baryon channels could yield bound states or near-threshold resonances at physical quark masses; results vary by channel and calculation.

Experimentally, searches in hadron–hadron scattering, hypernuclear systems, and heavy-ion collisions have not produced a confirmed dibaryon beyond the deuteron. The existence and properties of additional twobaryon states remain an area of active investigation, with implications for the understanding of baryon–baryon forces and non-perturbative QCD.