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The Quark Structure of Pentaquarks  [PDF]
O. Jahn,J. W. Negele,D. Sigaev
Physics , 2005,
Abstract: Motivated by the possible observation of the $\Theta^+(1530)$, we study the quark structure of pentaquark states in quenched lattice QCD. The complete set of 19 local sources that have the proper symmetry for positive or negative parity isoscalar pentaquarks is constructed, as well as a nonlocal source composed of two displaced ``good'' diquarks. Quantitative structure information is determined from diagonalizing the 19-dimensional correlation matrix and from calculating the overlaps of sources with the lattice eigenstates. The volume dependence of the overlap is studied to differentiate between scattering and localized resonant states. The positive parity state has a small component of two ``good'' diquarks, and its energy is too much higher than the negative parity state to be a candidate for the $\Theta^+(1530)$.
Heavy-Flavour Pentaquarks in a Chiral Constituent Quark Model  [PDF]
M. Genovese,J. -M. Richard,FL. Stancu,S. Pepin
Physics , 1997, DOI: 10.1016/S0370-2693(98)00187-7
Abstract: Within the chiral constituent quark model of Glozman and Riska, we discuss the stability of heavy pentaquarks, i.e. hadrons containing four light quarks and a heavy antiquark. The spin-dependent part of the Hamiltonian is dominated by the short-range part of the Goldstone-boson-exchange interaction. We find that these systems are not bound, having an energy above the lowest dissociation threshold into a baryon and a meson.
Magnetic moments of exotic pentaquarks in the chiral quark-soliton model  [PDF]
Hyun-Chul Kim,Michal Praszalowicz
Physics , 2003, DOI: 10.1016/j.physletb.2004.01.067
Abstract: We investigate the magnetic moments of the baryon antidecuplet within the framework of the chiral quark-soliton model in the chiral limit in a ``\emph{model-independent}'' approach. Sum rules for the magnetic moments are derived. The magnetic moment of $\Theta^{+}$ is found to be about $0.2\sim 0.3 \mu_{N}$.
Chiral symmetry and pentaquarks  [PDF]
Dmitri Diakonov
Physics , 2004,
Abstract: Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate pentaquark masses by some 500 MeV and why in the fully relativistic approach to baryons pentaquarks turn out to be light. I discuss briefly why it can be easier to produce pentaquarks at low than at high energies.
Hadron Structure Functions in a Chiral Quark Model  [PDF]
Leonard Gamberg,Herbert Weigel
Physics , 1999,
Abstract: We present a consistent regularization procedure for calculating hadron structure functions in a bosonized chiral quark model. We find that the Pauli-Villars regularization scheme is most suitable. We also summarize the phenomenology of structure functions calculated in the valence quark approximation.
Transversity structure of the pion in chiral quark models  [PDF]
Wojciech Broniowski,Enrique Ruiz Arriola,Alexander E. Dorokhov
Physics , 2011,
Abstract: We describe the chiral quark model evaluation of the transversity Generalized Parton Distributions (tGPDs) and related transversity form factors (tFFs) of the pion. The obtained tGPDs satisfy all necessary formal requirements, such as the proper support, normalization, and polynomiality. The lowest tFFs, after the necessary QCD evolution, compare favorably to the recent lattice QCD determination. Thus the transversity observables of the pion support once again the fact that the spontaneously broken chiral symmetry governs the structure of the Goldstone pion. The proper QCD evolution is crucial in these studies.
Spin Structure Functions in Chiral Quark Soliton Models  [PDF]
H. Weigel
Physics , 2002,
Abstract: In this talk I review studies of hadron structure functions in bosonized chiral quark models. Such models require regularization and I show that the two--fold Pauli--Villars regularization scheme not only fully regularizes the effective action but also leads the scaling laws for structure functions. This scheme is consistent with other computations of the pion structure function in that model. For the nucleon structure functions the present approach serves to determine the regularization prescription for structure functions whose leading moments are not given by matrix elements of local operators. Some numerical results are presented for the spin structure functions and the role of strange quarks is addressed.
$ΔΔ$ dibaryon structure in extended chiral SU(3) quark model  [PDF]
Lian-Rong Dai
Physics , 2005, DOI: 10.1088/0256-307X/22/9/018
Abstract: The structure of $\Delta\Delta$ dibaryon is studied in the extended chiral SU(3) quark model in which vector meson exchanges are included. The effect from the vector meson fields is very similar to that from the one-gluon exchange (OGE) interaction. Both in the chiral SU(3) quark model and in the extended chiral SU(3) quark model, the resultant mass of the $\Delta\Delta$ dibaryon is lower than the threshold of the $\Delta\Delta$ channel but higher than that of the $\Delta N\pi$ channel.
Electromagnetic Structure of the Nucleon in the Perturbative Chiral Quark Model  [PDF]
V. E. Lyubovitskij,Th. Gutsche,Amand Faessler
Physics , 2001, DOI: 10.1103/PhysRevC.64.065203
Abstract: We apply the perturbative chiral quark model (PCQM) at one loop to analyse the electromagnetic structure of nucleons. This model is based on an effective Lagrangian, where baryons are described by relativistic valence quarks and a perturbative cloud of Goldstone bosons. Including the electromagnetic interaction we first develop the formalism up to one-loop in the Goldstone boson fluctuation relying on renormalization by use of counterterms. Local gauge invariance is satisfied both on the Lagrangian level and also for the relevant baryon matrix elements in the Breit frame. We apply the formalism to obtain analytical expressions for the nucleon charge and magnetic form factors, which are expressed in terms of fundamental parameters of low-energy pion-nucleon physics (weak pion decay constant, axial nucleon coupling, strong pion-nucleon form factor) and of only one model parameter (radius of the nucleonic three-quark core). A detailed numerical analysis for the nucleon magnetic moments, charge and magnetic radii and also for the momentum dependence of form factors is presented.
Understanding the structure of $d^*(2380)$ in chiral quark model  [PDF]
F. Huang,P. N. Shen,Y. B. Dong,Z. Y. Zhang
Physics , 2015,
Abstract: The structure and decay properties of $d^*$ have been detailedly investigated in both the chiral SU(3) quark model and the extended chiral SU(3) quark model that describe the energies of baryon ground states and the nucleon-nucleon (NN) scattering data satisfactorily. By performing a dynamical coupled-channels study of the system of $\Delta\Delta$ and hidden-color channel (CC) with quantum numbers $I(J^P)=0(3^+)$ in the framework of the resonating group method (RGM), we find that the $d^*$ has a mass of about $2.38-2.42$ GeV and a root-mean-square radius (RMS) of about $0.76-0.88$ fm. The channel wave function is extracted by a projection of the RGM wave function onto the physical basis, and the fraction of CC component in the $d^*$ is found to be about $66\%-68\%$, which indicates that the $d^*$ is a hexaquark-dominated exotic state. Based on this scenario the partial decay widths of $d^*\to d \pi^0 \pi^0$ and $d^*\to d \pi^+\pi^-$ are further explicitly evaluated and the total width is then obtained by use of the branching ratios extracted from the measured cross sections of other possible decay channels. Both the mass and the decay width of $d^*$ calculated in this work are compatible with the data ($M\approx 2380$ MeV, $\Gamma\approx 70$ MeV) reported by WASA-at-COSY Collaboration.
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