No Arabic abstract
We present a new classification scheme of baryon ground states and resonances into SU(3) flavor multiplets. The scheme is worked out along a covariant formalism with relativistic constituent quark models and it relies on detailed investigations of the baryon spectra, the spin-flavor structure of the baryon eigenstates, the behaviour of their probability density distributions as well as covariant predictions for mesonic decay widths. The results are found to be quite independent of the specific types of relativistic constituent quark models employed. It turns out that a consistent classification requires to include also resonances that are presently reported from experiment with only two-star status.
Latest results from a study of baryon ground and resonant states within relativistic constituent quark models are reported. After recalling some typical spectral properties, the description of ground states, especially with regard to the nucleon and hyperon electromagnetic structures, is addressed. In the following, recent covariant predictions for pion, eta, and kaon partial decay widths of light and strange baryon resonances below 2 GeV are summarized. These results exhibit a characteristic pattern that is distinct from nonrelativistic or relativized decay studies performed so far. Together with a detailed analysis of the spin, flavor, and spatial structures of the wave functions, it supports a new and extended classification scheme of baryon ground and resonant states into SU(3) flavor multiplets.
The challenges with the molecular model of the multiquark systems are the identification of the hadronic molecules and the interaction between two color neutral hadrons. We study the di-hadronic molecular systems with proposed interaction potential as s-wave one boson exchange potential along with Screen Yukawa-like potential, and arrived with the proposal that within hadronic molecule the two color neutral hadrons experience the dipole-like interaction. The present study is the continuation of our previous study cite{arxiv-Rathaud-penta}. With the proposed interaction potential, the mass spectra of $Sigma_{s}K^{*}$, $Sigma_{c}K^{*}$, $Sigma_{b}K^{*}$, $Sigma_{s}D^{*}$, $Sigma_{c}D^{*}$, $Sigma_{b}D^{*}$, $Sigma_{s}B^{*}$, $Sigma_{c}B^{*}$, $Sigma_{b}B^{*}$, $Xi_{s}K^{*}$, $Xi_{c}K^{*}$, $Xi_{b}K^{*}$, $Xi_{s}D^{*}$, $Xi_{c}D^{*}$, $Xi_{b}D^{*}$, $Xi_{s}B^{*}$, $Xi_{c}B^{*}$, $Xi_{b}B^{*}$ meson-baryon molecules are predicted. The Weinberg compositeness theorem which provides clue for the compositeness of the state is used for determination of the scattering length and effective range. The present study predict $P_{c}(4450)$ pentaquark sate as $Sigma_{c}D^{*}$ molecule with $I(J^{P})=frac{1}{2}(frac{3}{2}^{-})$. The formalism also predicts some very interesting open as well as hidden flavour near threshold molecular pentaquark states.
The electromagnetic properties of baryon octet are studied in the perturbative chiral quark model (PCQM). The relativistic quark wave function is extracted by fitting the theoretical results of the proton charge form factor to experimental data and the predetermined quark wave function is applied to study the electromagnetic form factors of other octet baryons as well as magnetic moments, charge and magnetic radii. The PCQM results are found, based on the predetermined quark wave function, in good agreement with experimental data.
Spectrum of the doubly heavy tetraquarks, $bbbar qbar q$, is studied in a constituent quark model. Four-body problem is solved in a variational method where the real scaling technique is used to identify resonant states above the fall-apart decay thresholds. In addition to the two bound states that were reported in the previous study we have found several narrow resonant states above the $BB^*$ and $B^*B^*$ thresholds. Their structures are studied and are interpreted by the quark dynamics. A narrow resonance with spin-parity $J^P=1^+$ is found to be a mixed state of a compact tetraquark and a $B^*B^*$ scattering state. This is driven by a strong color Coulombic attraction between the $bb$ quarks. Negative-parity excited resonances with $J^P=0^-$, $1^-$ and $2^-$ form a triplet under the heavy-quark spin symmetry. It turns out that they share a similar structure to the $lambda$-mode of a singly heavy baryon as a result of the strongly attractive correlation for the doubly heavy diquark.
We present a path-integral hadronization for doubly heavy baryons. The two heavy quarks in the baryon are approximated as a scalar or axial-vector diquark described by a heavy diquark effective theory. The gluon dynamics are represented by a NJL-Model interaction for the heavy diquarks and light quarks, which leads to an effective action of the baryon fields after the quark and diquark fields are integrated out. This effective action for doubly heavy baryon includes the electromagnetic and electroweak interactions, as well as the interaction with light mesons. We also verify the Ward-Takahashi identity at the baryon level, obtain the Isgur-Wise function for weak transitions, and calculate the strong coupling constant of the doubly heavy baryon and pion. Numerical studies are also performed.