scholarly journals HYPERCENTRAL CONSTITUENT QUARK MODEL AND ISOSPIN DEPENDENCE

Author(s):  
M. M. GIANNINI ◽  
E. SANTOPINTO ◽  
A. VASSALLO
2008 ◽  
Vol 23 (07) ◽  
pp. 527-537 ◽  
Author(s):  
H. HASSANABADI ◽  
A. A. RAJABI ◽  
S. ZARRINKAMAR

The constituent quark model (CQM) has recently been widely used for the description of the internal structure of baryons. The baryon spectrum is usually well described, although various models are quite different. However, the study of baryon spectroscopy is not sufficient to distinguish among the various forms of quark dynamics. It would be interesting to consider the effect of an extra residual interaction among the quarks, which contains a dependence on isospin (or flavor). In the chiral constituent quark model the non-confining part of the potential is provided by the interaction with the Goldstone bosons, giving rise to a spin- and isospin-dependent part which is crucial for the description of the spectrum for energies lower than 1.7 GeV. In this work we have introduced an improved form of the hyperfine interaction and isospin dependent quark potential. The resulting description of the baryon spectrum was found to be satisfactory and we not only have included confinement potential at large separations, but also color charge and non-confining hyperfine interaction potentials. This combination of potentials yields spectra which are very close to the ones obtained in experiments.


2009 ◽  
Vol 24 (32) ◽  
pp. 2631-2637 ◽  
Author(s):  
NASRIN SALEHI ◽  
ALI AKBAR RAJABI

The static properties of protons are useful for understanding the quark structure of the proton. In his work we have introduced the hypercentral constituent quark model and isospin dependent potentials. Here constituent quarks interact with each other via a potential in which we have taken into account the three-body force effect and the standard two-body potential contributions. According to our model the static properties of protons containing u and d quarks are better than the other models and closer to experimental results. The two key ingredients of this improvement are the effective quark–gluon hypercentral potentials, and hyperfine interaction and isospin dependence potential. Recently, Schrödinger equation has been solved by Giannini but we have solved the Dirac equation exact analytically and we have shown that a considerable improvement in the description of the static properties of proton is obtained with an isospin dependent potential and the complete interaction including spin and isospin terms reproduces the position of the quark.


2001 ◽  
Vol 12 (4) ◽  
pp. 447-452 ◽  
Author(s):  
M.M. Giannini ◽  
E. Santopinto ◽  
A. Vassallo

2007 ◽  
Vol 34 (7) ◽  
pp. 1771-1782 ◽  
Author(s):  
W L Wang ◽  
F Huang ◽  
Z Y Zhang ◽  
Y W Yu ◽  
F Liu

2007 ◽  
Vol 22 (24) ◽  
pp. 4519-4535 ◽  
Author(s):  
A. MIRJALILI ◽  
K. KESHAVARZIAN

Sea quark distributions in the NLO approximation, based on the phenomenological valon model or constituent quark model are analyzed. We use the parametrized inverse Mellin transform technique to perform a direct fit with available experimental data and obtain the unknown parameters of the distributions. We try to extend the calculation to the NLO approximation for the singlet and nonsinglet cases in DIS phenomena. We do also the same calculation for electron–positron annihilation. The resulting sea distributions are effectively independent of the process used. The approach of complete RG improvement (CORGI) is employed and the results are compared with the standard approach of perturbative QCD in the [Formula: see text] scheme with a physical scale. The comparisons with data are in good agreement. As is expected, the results in the CORGI approach indicate a better agreement to the data than the NLO calculation in the standard approach.


2003 ◽  
Vol 50 (2) ◽  
pp. 263-272 ◽  
Author(s):  
M.M Giannini ◽  
E Santopinto ◽  
A Vassallo

2007 ◽  
Vol 76 (6) ◽  
Author(s):  
M. De Sanctis ◽  
M. M. Giannini ◽  
E. Santopinto ◽  
A. Vassallo

2005 ◽  
Vol 20 (08n09) ◽  
pp. 1797-1802 ◽  
Author(s):  
FL. STANCU

Light and heavy pentaquarks are described within a constituent quark model based on a spin-flavor hyperfine interaction. In this model the lowest state acquires positive parity. The masses of the light antidecuplet members are calculated dynamically using a variational method. It is shown that the octet and antidecuplet states with the same quantum numbers mix ideally due to SU (3)F breaking. Masses of the charmed antisextet pentaquarks are predicted within the same model.


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