multibaryon

Multibaryon is a term used in nuclear and particle physics to describe any system that contains more than one baryon. Baryons are fermions made of three quarks, the most familiar examples being protons and neutrons. Multibaryon systems range from ordinary nuclei, in which several nucleons are bound by the strong force, to exotic states consisting of multiple baryons bound together in ways not yet observed in ordinary matter.

Conventional nuclei such as the deuteron (a bound state of a proton and a neutron) and helium-3 or helium-4 are examples of multibaryon systems. The deuteron is the simplest stable bound baryon composite. The study of these systems informs models of nuclear forces and the behavior of baryons at low energy.

Exotic multibaryons include hypothetical bound states of two baryons (dibaryons) and more complex assemblies, sometimes called tribaryons, tetrabaryons, etc. The classic example is the proposed H-dibaryon (uuddss) introduced by Jaffe in 1977; despite extensive searches, no conclusive experimental evidence has been found.

Hypernuclei are real multibaryon systems in which one or more nucleons are replaced by hyperons, such as lambda or sigma particles. These systems provide a laboratory for studying hyperon–nucleon and hyperon–hyperon interactions and have implications for the equation of state of dense matter.

Multibaryon physics is studied with a combination of experimental scattering, spectroscopy, and reactions in nuclear and particle accelerators, as well as theoretical approaches including nuclear effective field theories and lattice quantum chromodynamics. In extreme environments such as high-energy heavy-ion collisions or the interiors of neutron stars, multibaryon interactions can play a significant role.