The theta^+ baryon in soliton models: large Nc QCD and the validity of rigid-rotor quantization

Abstract

A light collective theta+ baryon state (with strangeness +1) was predicted via rigid-rotor collective quantization of SU(3) chiral soliton models. This paper explores the validity of this treatment. A number of rather general analyses suggest that predictions of exotic baryon properties based on this approximation do not follow from large Nc QCD. These include an analysis of the baryon's width, a comparison of the predictions with general large Nc consistency conditions of the Gervais-Sakita-Dashen-Manohar type; an application of the technique to QCD in the limit where the quarks are heavy; a comparison of this method with the vibration approach of Callan and Klebanov; and the 1/Nc scaling of the excitation energy. It is suggested that the origin of the problem lies in an implicit assumption in the that the collective motion is orthogonal to vibrational motion. While true for non-exotic motion, the Wess-Zumino term induces mixing at leading order between collective and vibrational motion with exotic quantum numbers. This suggests that successful phenomenological predictions of theta+ properties based on rigid-rotor quantization were accidental.

19 pages; A shorter more readable version

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• Large-$N_c$ analysis of two-nucleon neutrinoless double beta decay and charge-independence-breaking contact terms
• Prospects for Pentaquark Production at Meson Factories
• Axial-vector transitions and strong decays of the baryon antidecuplet in the self-consistent SU(3) chiral quark-soliton model
• Heavy and Light Pentaquark Chiral Lagrangian
• Phenomenological constraints on the Jaffe-Wilczek model of pentaquarks
• The collective quantization of three-flavored Skyrmions revisited
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• The quantization of exotic states in SU(3) soliton models: A solvable quantum mechanical analog
• SU(3) constraints on cryptoexotic pentaquarks
• Electric properties of the baryon anti-decuplet in the SU(3) chiral quark-soliton model
• Positive parity pentaquark towers in large Nc QCD
• Soliton Picture for Pentaquarks
• The 35-plet Baryons from Chiral Soliton Models
• Strange results from chiral soliton models
• The Skyrme model predictions for the ${27}_{J=3/2}$ mass spectrum and the ${27}_{3/2}$-$\overline{10}$ mass splittings
• Constraints on narrow exotic states from K+p and K0_Lp scattering data
• Stability of the rotating SU(3) Skyrmion
• On the Decay of Soliton Excitations