Goldstone Boson Exchange Model Research Articles

Low-lying 1/2− hidden strange pentaquark states in the constituent quark model**Supported by National Natural Science Foundation of China (11675131, 11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)

We investigate the spectrum of the low-lying 1/2− hidden strange pentaquark states, employing the constituent quark model, and looking at two ways within that model of mediating the hyperfine interaction between quarks − Goldstone boson exchange and one gluon exchange. Numerical results show that the lowest 1/2− hidden strange pentaquark state in the Goldstone boson exchange model lies at ∼1570 MeV, so this pentaquark configuration may form a notable component in S11(1535) if the Goldstone boson exchange model is applied. This is consistent with the prediction that S11(1535) couples very strongly to strangeness channels.

Spectra of charmed and bottom baryons with hyperfine interaction**Supported by National Natural Science Foundation of China (11175020, 11575023, U1204115)

Up to now, the excited charmed and bottom baryon states have still not been well studied experimentally or theoretically. In this paper, we predict the mass of , the only L = 0 baryon state which has not been observed, to be 6069.2 MeV. The spectra of charmed and bottom baryons with the orbital angular momentum L = 1 are studied in two popular constituent quark models, the Goldstone boson exchange (GBE) model and the one gluon exchange (OGE) hyperfine interaction model. Inserting the latest experimental data from the “Review of Particle Physics", we find that in the GBE model, there exist some multiplets (Σc(b), and Ωc(b)) in which the total spin of the three quarks in their lowest energy states is 3/2, but in the OGE model there is no such phenomenon. This is the most important difference between the GBE and OGE models. These results can be tested in the near future. We suggest more efforts to study the excited charmed and bottom baryons both theoretically and experimentally, not only for the abundance of baryon spectra, but also for determining which hyperfine interaction model best describes nature.

Mixing of the low-lying three- and five-quarkΩstates with negative parity

Mixing of the low-1/2^{-}$ and $3/2^{-}$ is investigated, employing an instanton-induced quark-antiquark pair creation model, which precludes transitions between $s^{3}$ and $s^{4}\bar{s}$ configurations. Models with hyperfine interactions between quarks of three different kinds, namely, one-gluon-exchange, Goldstone-boson-exchange (GBE) and an instanton-induced interaction (INS) are called OGE, GBE and INS models, respectively. Numerical results show that the instanton-induced pair creation causes strong mixing between the three- and five-quark configurations with spin 3/2, and that this mixing decreases the energy of the lowest spin 3/2 states in all three different hyperfine interaction models to $\sim 1750\pm50$ MeV. On the other hand, transition couplings between $s^3$ and $s^{3}q\bar{q}$ states with spin 1/2 caused by instanton-induced $q\bar{q}$ creation is very small and the resulting mixing of three- and five-quark configurations in the OGE and INS models is negligible, while the mixing of the spin 1/2 states in GBE model is not, but effects of this mixing on energies of mixed states are also very small. Accordingly, the lowest $\Omega$ states with negative parity in all three hyperfine interactions models have spin 3/2.

Magnetic Moments and Electromagnetic Radii of Nucleon andΔ(1232) in an Extended Goldstone–Boson-Exchange Model

We derive the exchange currents of pseudoscalar, vector, andscalar mesons from Feynman diagrams, and use them to calculate themagnetic form factors of nucleon and Δ(1232). The magneticmoments and electromagnetic radii are obtained by using those formfactors and the parameters determined from the masses of nucleonand Δ(1232). We find the magnetic moments andelectromagnetic radii of nucleon and Δ(1232) can beproduced very well in the extended Goldstone–Boson-exchange model in which all of pseudoscalar, vector, and scalar meson nonetare included. The magnetic moments of Δ(1232) are closer toexperiment values and results from lattice calculation than theresults obtained by the model without other mesons except for pionand sigma.

Magnetic moments of L = 1 negative parity N* resonances in different models

In this paper, by using harmonic-oscillator wavefunctions of different interaction models: one-pion-exchange model (OPE), only pseudoscalar meson exchange model (OPsE), the extended Goldstone-boson-exchange model (GBE), and one-gluon-exchange model (OGE), we calculate the magnetic moments of L = 1 negative parity N* resonances, and compare them with the results of the chiral unitary model (CUM). We find that the results for N(1535) of the extended GBE and OGE are similar to those of the CUM.

Negative parity [formula omitted] resonances in an extended GBE

In this paper, we calculate the masses and mixing angles of L=1 negative parity N ∗ resonances in an extended GBE (Goldstone-boson-exchange model) with harmonic-oscillator wave functions. By using those mixing angles, we get their photo-production amplitudes, and compare them with experimental data and the results of OPE (one-pion-exchange model), OPsE (only pseudoscalar meson exchange model), and OGE (one-gluon-exchange model). We find that the extended GBE gives right internal wave functions. It is essential to extend GBE to include not only pseudoscalar meson exchanges but also vector meson exchanges.

WHICH CONSTITUENT QUARK MODEL IS BETTER?

A comparative study has heen done by calculating the effective baryon-baryon interactions of the 64 lowest channels consisting of octet and decuplet baryons with three constituent quark models: the extended quark gluon exchange model, the Goldstone boson exchange model and the quark gluon meson exchange hybrid model. We find that these three models give similar results for 44 channels. Further tests of these models are discussed.

The Effective Degree of Freedom of Low Energy QCD**The project partly supported by NSF, SED and SSTD of China, and partly by the US Department of Energy under contract W-7405-ENG-36

The adiabatic effective baryon-baryon interactions and dibaryon candidates are studied systematically with three constituent quark models based on different effective degrees of freedom: Glozman–Riska–Brown Goldstone boson exchange model based on constituent quark and Goldstone boson coupling; Fujiwara model based on constituent quark gluon coupling and Nijmegen one-boson exchange; QDCSM based on constituent quark and gluon coupling with quark delocalization and color screening. We find that the three models predicted the similar effective baryon-baryon interactions for roughly two thirds among the 64 states consisted of octet and decuplet baryons. The differences among three models and their separate characteristics are also studied.

Important configurations forNNprocesses in a Goldstone boson exchange model

We study the short-range nucleon-nucleon interaction in a nonrelativistic chiral constituent quark model by diagonalizing a Hamiltonian containing a linear confinement and a Goldstone boson exchange interaction between quarks. A finite six-quark basis obtained from single particle cluster model states was previously used. Here we show that the configurations which appear naturally through the use of molecular orbitals, instead of cluster model states, are more efficient in lowering the six-quark energy.

Positive parity pentaquarks in a Goldstone boson exchange model

We study the stability of the pentaquarks uuddQbar, uudsQbar and udssQbar (Q = c, b, or t) of positive parity in a constituent quark model based on Goldstone boson exchange interaction between quarks. The pentaquark parity is the antiquark parity times that of a quark excited to a p-shell. We show that the Goldstone boson exchange interaction favors these pentaquarks much more than the negative parity ones of the same flavour content but all quarks in the ground state. We find that the nonstrange pentaquarks are stable against strong decays.