Charge radii of octet and decuplet baryons

2010

The electromagnetic form factors are the most fundamental quantities to describe the internal structure of the nucleon and the shape of a spatially extended particle is determined by its intrinsic quadrupole moment which can be related to the charge radii. We have calculated the electromagnetic form factors, nucleon charge radii and the intrinsic quadrupole moment of the nucleon in the framework of chiral constituent quark model. The results obtained are comparable to the latest experimental studies and also show improvement over some theoretical interpretations.

Physical Review D, 2006

We investigate the electric form factors and charge radii of the pentaquark baryons within the framework of the chiral quark-soliton model. We consider the rotational 1/N c and linear m s corrections, assuming isospin symmetry and employing the symmetry-conserving quantization. The flavor-decomposed charge densities of the Θ + are presented. The electric form factors and charge radii of the charged pentaquark baryons turn out to be very similar to those of the corresponding octet baryons. The charge radii of the neutral pentaquark baryons are obtained to be very tiny and positive. The strange electric form factor of the pentaquark proton is shown to be larger than the corresponding one of the proton by around 20 %. We also present the charge radii of the baryon decuplet for comparison.

Physical Review D, 2006

The electromagnetic properties of the baryon octet are calculated in quenched QCD on a 20 3 × 40 lattice with a lattice spacing of 0.128 fm using the fat-link irrelevant clover (FLIC) fermion action. FLIC fermions enable simulations to be performed efficiently at quark masses as low as 300 MeV. By combining FLIC fermions with an improved-conserved vector current, we ensure that discretisation errors occur only at O(a 2 ) while maintaining current conservation. Magnetic moments and electric and magnetic radii are extracted from the electric and magnetic form factors for each individual quark sector. From these, the corresponding baryon properties are constructed. Our results are compared extensively with the predictions of quenched chiral perturbation theory. We detect substantial curvature and environment sensitivity of the quark contributions to electric charge radii and magnetic moments in the low quark mass region. Furthermore, our quenched QCD simulation results are in accord with the leading non-analytic behaviour of quenched chiral perturbation theory, suggesting that the sum of higher-order terms makes only a small contribution to chiral curvature.

Physical Review D, 2003

Several recent papers -using effective QCD chiral Lagrangians-reproduced results obtained with the general QCD parameterization (GP). These include the baryon 8+10 mass formula, the octet magnetic moments and the coincidental nature of the "perfect" (µ p /µ n ) = −(3/2) ratio. Although we anticipated that the GP covers the case of chiral treatments, the above results explicitly exemplify this fact. Also we show by the GP that -in any model or theory (chiral or non chiral) reproducing the results of exact QCD-the Franklin (Coleman Glashow) sum rule for the octet magnetic moments must be violated. 1.Introduction: Chiral results and GP results 1-In a recent publication Durand et al.[1] (see also [2]) derived, by an effective chiral Lagrangian, the same 8+10 baryon mass formula that, using the general QCD parameterization (GP) [3], [4], had been obtained in [5] and re-discussed in [6]. Also they derive in Ref.[1] an expression for the baryon octet magnetic moments similar to that obtained with the GP in Refs.[3, 4, 6, 9]. They kindly acknowledged all this in [1]. 2-These interesting results of Durand et al. add to one by Leinweber et al.. In Ref.

Chinese Journal of Physics- Taipei-

The hypercentral Constituent Quark Model (hCQM) for the baryon structure is reviewed and its applications are systematically discussed. The model is based on a simple form of the quark potential, which contains a Coulomb-like interaction and a confinement, both expressed in terms of a collective space coordinate, the hyperradius. The model has only three free parameters, determined in order to describe the baryon spectrum. Once the parameters have been fixed, the model, in its non relativistic version, is used to predict various quantities of physical interest, namely the elastic nucleon form factors, the photocouplings and the helicity amplitudes for the electromagnetic excitation of the baryon resonances. In particular, the $Q^2$ dependence of the helicity amplitude is quite well reproduced, thanks to the Coulomb-like interaction. The model is reformulated in a relativistic version by means of the Point Form hamilton dynamics. While the inclusion of relativity does not alter the r...

Physical Review D, 2003

We develop a straightforward method to compute charge radii and quadrupole moments for baryons both with and without strangeness, when the number of QCD color charges is N c. The minimal assumption of the single-photon exchange ansatz implies that only two operators are required to describe these baryon observables. Our results are presented so that SU(3) flavor and isospin symmetry breaking can be introduced according to any desired specification, although we also present results obtained from two patterns suggested by the quark model with gluon exchange interactions. The method also permits to extract a number of model-independent relations; a sample is r 2 Λ /r 2 n = 3/(N c + 3), independent of SU(3) symmetry breaking.

2002

Baryon charge radii and quadrupole moments are calculated in a quark model generalized to an arbitrary number (NC) of colors. Several relations among the charge radii and quadrupole moments are found. In particular, the relation Q{p-> Delta +} = (1)/(&surd; {2)}r2n between the neutron charge radius r2n and the p --> Delta+ transition quadrupole moment Qp --> Delta is shown to hold for physical baryons as well in the large Nc limit.

Proceedings of Light Cone 2010: Relativistic Hadronic and Particle Physics — PoS(LC2010)

The electromagnetic form factors are the most fundamental quantities to describe the internal structure of the nucleon and the shape of a spatially extended particle is determined by its intrinsic quadrupole moment which is first order moment of the charge density operator. With some experimental indications of a deformed nucleon, we have calculated the intrinsic quadrupole moment of the octet and decuplet baryons in the framework of chiral constituent quark model χCQM which is quite successful in explaining some of the important baryon properties in the nonperturbative regime.

Nuclear Physics A, 2002

The hypercentral constituent quark model contains a spin independent three-quark interaction inspired by lattice QCD calculations which reproduces the average energy of SU (6) multiplets [1]. The splittings are obtained with a residual generalized SU (6)-breaking interaction including an isospin dependent term . The long standing problem of the Roper is absent and all the 3-and 4-star states are well reproduced. The model has been used in a systematic way for transverse and longitudinal electromagnetic transition form factor of the 3-and 4-star and also for the missing resonances. The prediction of the electromagnetic helicity amplitudes agrees quite well with the data except for low Q 2 , showing that it can supply a realistic set of quark wave functions. In particular we report the calculated helicity amplitude A 1/2 for the S11(1535), which is in agreement with the TJNAF data .

2000

We show how one may define baryon constituent quarks in a rigorous manner, given physical assumptions that hold in the large-Nc limit of QCD. This constituent picture gives rise to an operator expansion that has been used to study large-Nc baryon observables; here we apply it to the case of charge radii of the N and ∆ states, using minimal dynamical assumptions. For example, one finds the relation r p − r ∆+ = r n − r ∆0 to be broken only by three-body, O(1/N c ) effects for any Nc. 11.15.Pg, 14.20.-c, 12.39.-x, 13.40.Gp Typeset using REVTEX [email protected] [email protected]