Exotic baryon

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Ordinary baryons are bound states of 3 quarks. Exotic baryons, if they exist, would be bound states of 3 quarks and additional particles. These additional particles can be quarks. The pentaquark, would consist of four quarks and an anti-quark [1]. Another exotic baryon which consists only of quarks is the H dibaryon [2][3]. The H dibaryon consists of two up quarks, two down quarks and two strange quarks. Unlike the pentaquark, this particle would be long lived or even stable. There have been unconfirmed claims of detections of pentaquarks and dibaryons [4][5].

Several types of exotic baryons which require physics beyond the standard model have been conjectured in order to explain specific experimental anomalies. There is no independent experimental evidence for any of these particles. One example is supersymmetric R-baryons[6], which are bound states of 3 quarks and a gluino. The lightest R-baryon is denoted as S0 and consists of an up quark, a down quark, a strange quark and a gluino. This particle is expected to be long lived or stable and has been invoked to explain ultrahigh energy cosmic rays[7] [8]. Stable exotic baryons are also candidates for strongly interacting dark matter.

[edit] References

  1. ^  D. Diakonov, V. Petrov, M. Polyakov, Exotic Anti-Decuplet of Baryons: Prediction from Chiral Solitons Z.Phys. A359 (1997) 305-314 "We predict an exotic Z+ baryon..."
  2. ^  G. R. Farrar and G. Zaharijas, Nuclear and nucleon transitions of the H di-baryon, Phys. Rev. D 70, 014008 (2004) preprint.
  3. ^  R. Jaffe, Perhaps a stable dihyperon..., Phys. Rev. Lett. 38, 195 (1977).
  4. ^  A. R. Dzierba, C. A. Meyer), and A. P. Szczepaniak, Reviewing the Evidence for Pentaquarks, J.Phys.Conf.Ser. 9 (2005) 192-204 "...the experimental evidence for pentaquarks is very weak."
  5. ^  J. Belz et al. (BNL E888 Collaboration} Search for the Weak Decay of an H Dibaryon (1997) "Our search has yielded two candidate events..."
  6. ^  G. R. Farrar, Detecting Gluino-Containing Hadrons, Phys. Rev. Lett. 76, 4111 (1996) preprint.
  7. ^  D. Chung, G. R. Farrar and E. W. Kolb, Are ultrahigh energy cosmic rays signals of supersymmetry?, Phys. Rev. D 57, 4606 (1998) preprint.
  8. ^ I. F. M. Albuquerque, G. Farrar and E. W. Kolb, Exotic massive hadrons and ultra-high energy cosmic rays, Phys. Rev. D 59, 015021 (1999) preprint.
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