Spectrum of the excited $N^{\ast }$ and ${\Delta }^{\ast }$ baryons in a relativistic chiral quark model

Abstract

The spectrum of the SU(2) flavor baryons is studied in the frame of a relativistic chiral quark potential model based on the one-pion and one-gluon exchange mechanisms. It is argued that the N* and Delta* resonances strongly coupled to the pi-N channel are identified with the orbital configurations $(1S_{1/2}{)}^2(nlj)$ with a single valence quark in the excited state (nlj). With the obtained selection rules based on the "chiral constraint", we show that it is possible to construct a schematic periodic table of baryon resonances, consistent with the experimental data and yielding no "missing resonances". A new original method for the treatment of the center of mass problem is suggested, which is based on the separation of the three-quark Dirac Hamiltonian into the parts, corresponding to the Jacobi coordinates. The numerical estimations for the energy positions of the Nucleon and Delta baryons (up to and including F-wave resonances), obtained within the field-theoretical framework by using time ordered perturbation theory, yield an overall good description of the experimental data at the level of the relativized CQM of S. Capstick and W. Roberts without any fitting parameters. The Delta(1232) is well reproduced. However, N g. s. and most of the radially excited baryon resonances (including Roper) are overestimated. Contrary, the first band of the orbitally excited baryon resonances with a negative parity are underestimated. At the same time, the second band of the orbitally excited Delta* states with the negative parity are mostly overestimated, while the N* states are close to the experimental boxes. The positive parity baryon resonances with J=5/2, 7/2 are close to the experimental data. At higher energies, where the experimental data are poor, we can extend our model schematically and predict an existence of seven N* and four Delta* new states with larger spin values.

19 pages, 6 figures, 2 tables. The results and text have been updated. arXiv admin note: text overlap with arXiv:1103.3661

References in corpus (12)

• Excited state baryon spectroscopy from lattice QCD
• Light Hadron Masses from Lattice QCD
• Charmonium potential from full lattice QCD
• Resolution of the Proton Spin Problem
• P-wave excited baryons from pion- and photo-induced hyperon production
• Updated analysis of meson-nucleon sigma terms in the perturbative chiral quark model
• Low-lying Odd-parity States of the Nucleon in Lattice QCD
• Quark-meson coupling model with the cloudy bag
• Ordering of Spin-$\frac{1}{2}$ Excitations of the Nucleon in Lattice QCD
• Ground-state baryon masses in the perturbative chiral quark model
• Interquark potential for the charmonium system with almost physical quark masses
• Relativistic structure of one-meson and one-gluon exchange forces and the lower excitation spectrum of the Nucleon and the Delta

Cited by in corpus (2)

• Meson cloud contributions to baryon axial form factors
• Analysis of excited quark propagator effects on neutron charge form factor