Dibaryon

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H dibayron.jpg

In particle physics 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 [5] and dibaryons [6] 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.[7] 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.

In 2014 an unstable Dibaryon was detected at the Jülich Research Center at about 2380 MeV. The particle existed for 10-23 seconds and was named d*(2380).[8]

See also[edit]

  • Deuteron, the only known stable composite particle that consist of six quarks.
  • Diproton, an extremely unstable dibaryon.
  • Dineutron, another extremely unstable dibaryon.

References[edit]

  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. ^ V. A. Ambartsumyan and G. S. Saakyan, Astron Zh. 37, 193 (1960).
  6. ^ Shigenori Kagiyama, Akihiro Nakamura and Toshihiro Omodaka; Compressible bag model and dibaryon stars; Zeitschrift für Physik C Particles and Fields; Volume 56, Number 4 / December, 1992
  7. ^ 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
  8. ^ "Evidence for a New Resonance from Polarized Neutron-Proton Scattering", http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.202301