Dibaryon

Dibaryons are a large family of hypothetical particles that would consist of six quarks of any flavours. They are predicted to be fairly stable once formed. Robert Jaffe proposed the existence of a possibly stable H dibaryon (with the quark composition udsuds), made by combining two uds hyperons, in 1977.^[1]

A number of experiments have been suggested to detect dibaryon decays and interactions. Several candidate dibaryon decays were observed but not confirmed in the 1990s.^[2][3][4]

There is a theory that strange particles such as hyperons and H dibaryons could form in the interior of a neutron star, changing its mass-radius ratio in ways that might be detectable. Conversely, measurements of neutron stars set constraints on possible dibaryon properties.^[5][6] Theory suggests that a large fraction of neutrons could turn into hyperons and merge into dibaryons during the early part of a neutron star to black hole collapse^{[citation needed]}. These dibaryons would very quickly dissolve into quark-gluon plasma during the collapse, or go into some currently unknown state of matter.

References

1. ^ R.L. Jaffe (1977). "Perhaps a Stable Dihyperon?". Physical Review Letters 38 (5): 195. Bibcode 1977PhRvL..38..195J. doi:10.1103/PhysRevLett.38.195. 
2. ^ BNL-E888 Collaboration (J. Belz et al.) "Search for the weak decay of an H dibaryon", Phys. Rev. Lett. 76:3277-3280 (1996) arXiv:hep-ex/9603002
3. ^ BNL E836 Collaboration (R.W. Stotzer et al.) "Search for H dibaryon in He-3 (K-, k+) Hn", Phys. Rev. Lett. 78:3646-3649 (1997)
4. ^ KTeV Collaboration (A. Alavi-Harati et al.) "Search for the weak decay of a lightly bound H0 dibaryon", Phys. Rev. Lett. 84:2593-2597 (2000), arXiv:/hep-ex/9910030
5. ^ A. Faessler, A. J. Buchmann, M. I. Krivoruchenko, Constraints to coupling constants of the ω- and σ-mesons with dibaryons, Phys. Rev. C56, 1576 (1997) arXiv:nucl-th/9706080
6. ^ F. Weber, R. Negreiros, P. Rosenfield, "Neutron Star Interiors and the Equation of State of Superdense Matter.", Invited review talk presented at "Neutron Stars and Pulsars: About 40 years after the discovery", Bad Honnef, Germany, 2006. To be published in Springer Lecture Notes arXiv:0705.2708