Hdibaryon

The Hdibaryon, also spelled H-dibaryon, is a hypothetical six-quark state with quark content uuddss. Proposed by Robert Jaffe in 1977 using the MIT bag model, it would form a color-singlet, flavor-singlet, spin-0 particle carrying baryon number 2, electric charge 0, and strangeness -2. Because it is a compact hexaquark, it could be distinct from bound two-Lambda systems.

Its mass and stability depend on strong interaction dynamics. If the H-dibaryon mass lies below the Lambda-Lambda threshold (about 2230 MeV), strong decays would be forbidden and the particle would be stable against strong interactions, decaying only via weak processes with a relatively long lifetime for a hadron. If heavier, it would decay promptly through strong or electromagnetic channels.

Experimental searches have not found conclusive evidence for the H-dibaryon. Investigations in double-Lambda hypernuclei, heavy-ion collisions, and dedicated missing-mass experiments have set limits on production rates and lifetimes. Early claims of signals were not confirmed. Lattice QCD studies have increasingly constrained the mass, with most simulations at physical quark masses indicating the H-dibaryon is not bound, though results vary by calculation and approach.

Significance: The existence of a stable or long-lived H-dibaryon would have implications for quantum chromodynamics and the behavior of dense strange matter in neutron stars, potentially affecting the equation of state and transport properties. It remains a topic of active theoretical and experimental interest.