Excited baryons in large [Formula Presented] QCD reexamined

The resonance picture versus single-quark excitations

Thomas D. Cohen, Richard Lebed

Research output: Contribution to journalArticle

Abstract

We analyze excited baryon properties via a [Formula Presented] expansion from two perspectives: as resonances in meson-nucleon scattering, and as single-quark excitations in the context of a simple quark model. For both types of analysis one can derive novel patterns of degeneracy that emerge as [Formula Presented] and that are shown to be compatible with one another. This helps justify the single-quark excitation picture and may give some insight into its successes. We also find that in the large [Formula Presented] limit one of the [Formula Presented] baryons does not couple to the [Formula Presented] channel but couples to the [Formula Presented] channel. This is empirically observed in the [Formula Presented] which couples very weakly to the [Formula Presented] channel and quite strongly to the [Formula Presented] channel. The comparatively strong coupling of the [Formula Presented] to the [Formula Presented] channel and weak coupling to [Formula Presented] channel is also predicted. In the context of the simple quark model picture we reproduce expressions for mixing angles that are accurate up to [Formula Presented] corrections and are in good agreement with mixing angles extracted phenomenologically.

Original languageEnglish (US)
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Volume67
Issue number9
DOIs
StatePublished - Jan 1 2003

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baryons
quantum chromodynamics
quarks
excitation
quark models
mesons
expansion

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Physics and Astronomy (miscellaneous)

Cite this

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abstract = "We analyze excited baryon properties via a [Formula Presented] expansion from two perspectives: as resonances in meson-nucleon scattering, and as single-quark excitations in the context of a simple quark model. For both types of analysis one can derive novel patterns of degeneracy that emerge as [Formula Presented] and that are shown to be compatible with one another. This helps justify the single-quark excitation picture and may give some insight into its successes. We also find that in the large [Formula Presented] limit one of the [Formula Presented] baryons does not couple to the [Formula Presented] channel but couples to the [Formula Presented] channel. This is empirically observed in the [Formula Presented] which couples very weakly to the [Formula Presented] channel and quite strongly to the [Formula Presented] channel. The comparatively strong coupling of the [Formula Presented] to the [Formula Presented] channel and weak coupling to [Formula Presented] channel is also predicted. In the context of the simple quark model picture we reproduce expressions for mixing angles that are accurate up to [Formula Presented] corrections and are in good agreement with mixing angles extracted phenomenologically.",
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AU - Lebed, Richard

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N2 - We analyze excited baryon properties via a [Formula Presented] expansion from two perspectives: as resonances in meson-nucleon scattering, and as single-quark excitations in the context of a simple quark model. For both types of analysis one can derive novel patterns of degeneracy that emerge as [Formula Presented] and that are shown to be compatible with one another. This helps justify the single-quark excitation picture and may give some insight into its successes. We also find that in the large [Formula Presented] limit one of the [Formula Presented] baryons does not couple to the [Formula Presented] channel but couples to the [Formula Presented] channel. This is empirically observed in the [Formula Presented] which couples very weakly to the [Formula Presented] channel and quite strongly to the [Formula Presented] channel. The comparatively strong coupling of the [Formula Presented] to the [Formula Presented] channel and weak coupling to [Formula Presented] channel is also predicted. In the context of the simple quark model picture we reproduce expressions for mixing angles that are accurate up to [Formula Presented] corrections and are in good agreement with mixing angles extracted phenomenologically.

AB - We analyze excited baryon properties via a [Formula Presented] expansion from two perspectives: as resonances in meson-nucleon scattering, and as single-quark excitations in the context of a simple quark model. For both types of analysis one can derive novel patterns of degeneracy that emerge as [Formula Presented] and that are shown to be compatible with one another. This helps justify the single-quark excitation picture and may give some insight into its successes. We also find that in the large [Formula Presented] limit one of the [Formula Presented] baryons does not couple to the [Formula Presented] channel but couples to the [Formula Presented] channel. This is empirically observed in the [Formula Presented] which couples very weakly to the [Formula Presented] channel and quite strongly to the [Formula Presented] channel. The comparatively strong coupling of the [Formula Presented] to the [Formula Presented] channel and weak coupling to [Formula Presented] channel is also predicted. In the context of the simple quark model picture we reproduce expressions for mixing angles that are accurate up to [Formula Presented] corrections and are in good agreement with mixing angles extracted phenomenologically.

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