An Original Didactic of the Standard Model “The Particle’s Geometric Model” (Nucleons and K-Mesons)

This paper shows a didactic model (PGM), and not only, but representative of the Hadrons described in the Standard Model (SM). In this model, particles are represented by structures corresponding to geometric shapes of coupled quantum oscillators (IQuO). By the properties of IQuO one can define the electric charge and that of color of quarks. Showing the “aurea” (golden) triangular shape of all quarks, we manage to represent the geometric combinations of the nucleons, light mesons, and K-mesons. By the geometric shape of W-bosons, we represent the weak decay of pions and charged Kaons and neutral, highlighting in geometric terms the possibilities of decay in two and three pions of neutral Kaon and the transition to anti-Kaon. In conclusion, from this didactic representation, an in-depth and exhaustive phenomenology of hadrons emerges, which even manages to resolve some problematic aspects of the SM.

Quark Mass Dependence of Nucleon Magnetic Moment and Charge Radii

Understanding hadron structure within the framework of QCD is an extremely challenging problem. Our purpose here is to explain the model-independent consequences of the approximated chiral symmetry of QCD for two famous results concerning the quark structure of the nucleon. We show that both the apparent success of the constituent quark model in reproducing the ratio of proton to neutron magnetic moments and the apparent success of the Foldy term in reproducing the observed charge radius of the neutron are coincidental. That is, a relatively small change of the current quark mass would spoil both results.

Associations in the Two-Nucleon Transfer Reactions

On the basis of the association theory of nuclear structure, we have studied the （t, p） reaction. Study was carried out with the distorted plane waves of triton and of proton. It has been suggested that bineutron association is acceptable if the time during which the association maintains its structure, is large compared with the time when neutrons are in a dissociated form, and there is no exchange of nucleons between fragments associations. The cross section is written as a product of two factors, one is the spectroscopic factor which reflects the nature of the nuclear structure concerned and the other describes the process in which the target nucleus captures two nucleons as a cluster into an orbit which is characterized by a form factor. In the argument, that the radial wave function of two neutrons which form association captured nuclei close to each other, this leads to the formation of bineutron association on the nuclei surface. In this approach, the proton is emitted at the same point, which is captured bineutron association.

A Universal Binding Mechanism in Molecular Covalent Bonding and Nucleon-Nucleon Interaction

In the hydrogen molecular ion, the kinetic energy lowering of the electron is associated with its delocalization due to electron exchange between the two protons of the molecule. This decrease in the kinetic energy of the exchanged electron in the hydrogen molecular ion and the decrease in the dynamical mass of the two exchanged pions in the nucleon-nucleon interaction are at the origin of the attraction mechanism in the molecular covalent bonding and in the nuclear interaction. Based on this unitary approach of the attraction mechanism, the formulas of molecular potential and central nucleon-nucleon potential were derived. The decrease in the mass of the exchanged pions in the nucleon-nucleon bound state, actually means the decrease in the mass of the nucleons. This nucleon mass decrease could be a manifestation of the partial chiral symmetry restoration in nuclear matter.

Hypernuclei as a laboratory to test hyperon–nucleon interactions

Directed flow(v_(1))of the hypernuclei ^(3)_(Λ)H and ^(4)_(Λ)H have been observed in mid-central Au+Au collisions at√^(s)NN=3 GeV at RHIC.This measurement opens up a new possibility for studying hyperon–nucleon(Y–N)interaction under finite pressure.In addition,multi-strangeness hypernuclei provide a venue to probe hyperon–nucleon–nucleon(Y–N–N)and even hyperon–hyperon–nucleon(Y–Y–N)interactions.Hypernuclei are important for making connection between nuclear collisions and the equation of state which governs the inner structure of compact stars.

Experimental study of intruder components in light neutron-rich nuclei via single-nucleon transfer reaction

With the development of radioactive beam facilities,studies concerning the shell evolution of unstable nuclei have recently gained prominence.Intruder components,particularly s-wave intrusion,in the low-lying states of light neutron-rich nuclei near N=8 are of importance in the study of shell evolution.The use of single-nucleon transfer reactions in inverse kinematics has been a sensitive tool that can be used to quantitatively investigate the single-particle orbital component of selectively populated states.The spin-parity,spectroscopic factor(or single-particle strength),and effective singleparticle energy can all be extracted from such reactions.These observables are often useful to explain the nature of shell evolution,and to constrain,check,and test the parameters used in nuclear structure models.In this article,the experimental studies of the intruder components in lowlying states of neutron-rich nuclei of He,Li,Be,B,and C isotopes using various single-nucleon transfer reactions are reviewed.The focus is laid on the precise determination of the intruder s-wave strength in low-lying states.

Electromagnetic nature of the nuclear forces and a toroid model of nucleons in atomic nuclei

In this paper we consider nucleons as tori, rotating with a constant angular velocity around the straight line passing through their mass centre (geometric centre) and perpendicular to their plane of rotation. We theoretically determine the corresponding potential energy and the force of interaction between pairs of nucleons, using our precise analytical formulas for the electrostatic interaction between two spheres with arbitrary radii and charges, which we derive using experimentally obtained results for the radii and the masses of the nucleons. From the values for binding energy found through our method, it follows that nuclear forces are electromagnetic in nature. In terms of magnitude of the force of interaction between proton and neutron, we obtain that Coulomb's forces are short-range. Our toroid model explains the experimental results not only for binding energy, but also for the radius, magnetic moment and the spin of the nuclei of atoms.

Nucleon-nucleon interactions in the double folding model for fusion reactions

Nucleus-nucleus potentials are determined in the framework of double folding model for M3Y-Reid and M3Y- Paris effective nucleon-nucleon （NN） interactions. Both zero-range and finite-range exchange parts of NN interactions are considered in the folding procedure. In this paper the spherical projectile-spherical target system 16O＋^2008Pb is selected for calculating the barrier energies, fusion cross sections and barrier distributions with the density-independent and density-dependent NN interactions on the basis of M3Y-Reid and M3Y Paris NN interactions. The barrier energies become lower for Paris NN interactions in comparison with Reid NN interactions, and also for finite-range exchange part in comparison with zero-range exchange part. The density-dependent NN interactions give similar fusion cross sections and barrier distributions, and the density-independent NN interaction causes the barrier distribution moving to a higher position. However, the density-independent Reid NN interaction with zero-range exchange part gives the lowest fusion cross sections. We find that the calculated fusion cross sections and the barrier distributions are in agreement with the experimental data after renormalization of the nuclear potential due to coupled-channel effect.

The Nucleon-Actinide Global Optical Model Potential Below 300 MeV

A set of new global phenomenological optical model potential parameters has been obtained in the mass range of target nuclei 220≤A≤260 with incident energies below 300 MeV, by simultaneously fitting the experimental data of 232Th and 23Su, and these potential parameters are analyzed and used to calculate the reaction cross sections, energy spectra and double differ- ential cross sections for p＋232Th reaction. Comparison of calculated results using these potential parameters with available experimental data shows that the present form of global optical model potential could reproduce experimental data for both the neutron and the proton.

Effects of Tensor Couplings on Nucleonic Direct URCA Processes in Neutron Star Matter

The relativistic neutrino emissivity of the nucleonic direct URCA processes in neutron star matter is investigated within the relativistic Hartree-Fock approximation. We particularly study the influences of the tensor couplings of vector mesons ω and ρ on the nucleonic direct URCA processes. It is found that the inclusion of the tensor couplings of vector mesons w and p can slightly increase the maximum mass of neutron stars. In addition, the results indicate that the tensor couplings of vector mesons ω and ρ lead to obvious enhancement of the total neutrino emissivity for the nucleonic direct URCA processes, which must accelerate the cooling rate of the non- superfluid neutron star matter. However, when considering only the tensor coupling of vector meson ρ, the neutrino emissivity for the nucleonic direct URCA processes slightly declines at low densities and significantly increases at high densities. That is, the tensor coupling of vector meson ρ leads to the slow cooling rate of a low-mass neutron star and rapid cooling rate of a massive neutron star.

A set of new nucleon coupling constants and the proto neutron star matter

Using a new set of nucleon coupling constants CZll the properties of a proto neutron star are examined within the framework of the relativistic mean-field theory for the baryon octet system. It is found that the relative number density of A,≡ , and ≡0 for CZll are all smaller than those for GL97 and for both CZ11 and GL97, ∑-∑0 and ∑＋ do not appear. It is also found that the pressure and the maximum mass for CZll are all smaller than those for GL97. The maximum mass for CZ11 decreases by approximately 9 percent compared with that for GL97.

Charged Multiplicity Density and Number of Participant Nucleons in Relativistic Nuclear Collisions

The energy and centrality dependencies of charged particle pseudorapidity density in relativistic nuclear collisions were studied using a hadron and string cascade model, JPCIAE. Both the relativistic experimental data and the PHOBOS and PHENIX Au+Au data at RHIC energy could be fairly reproduced within the framework of JPCIAE model and without retuning the model parameters. The predictions for collisions at the LHC energy were also given. We computed the participant nucleon distributions using different methods. It was found that the number of participant nucleons is not a well defined variable both experimentally and theoretically. Thus it may be inappropriate to use the charged particle pseudorapidity density per participant pair as a function of the number of participant nucleons for distinguishing various theoretical models.

Effects of the HMT on Nucleon Collective Flows within BUU Transport Model

Within the framework of a semiclassical Boltzmann-Uehling-Uhlenbeck （BUU） transport model, the high mo- mentum tail （HMT） effects of nucleon momentum distribution in the nucleus on the nucleon collective flows are studied in semieentral Au＋Au collisions. The HMT due to the isospin-dependent short-range correlations causes a smaller value of the collective flows. We find that the HMT effects on the nucleon collective flows are remarkable at beam energy of 300 MeV/nucleon and become weak as the incident beam energy increases. The results indicate that for the collective flow studies at intermediate energies, the HMT of nucleon momentum distribution in nucleus should be taken into account in transport models.

Nucleon-Nucleon Interaction in Constituent Quark Models

By using the chiral quark model and the quark delocalization colour screening model,the phase shifts of nucleonnucleon scattering for high partial waves are studied.The results of both the models are almost equivalent.None of the quark models used have found any resonance-like structure in^(3)F_(2),^(3)F_(3),^(3)F_(4)and^(3)H_(4)partial waves.

Approach to Perturbative QCD Results in Transition Amplitudes of NucleonNegative-Parity Resonances

The scaling behaviors of the nucleon resonance transition amplitudes from perturbative QCD (PQCD) are utilized to parametrize the amplitudes of the first negative-parity nucleon resonance . Our analysis indicates that the constraints of the transition amplitude for the resonance at the limit by QCD sum rule calculations are not applicable at a moderate range of compared with the present available data if the contribution of is dominant in the limit.

Nucleon Spin Structure Functions in the Resonance Region and the Duality

We discuss the nucleon spin structure function g1 and the difference between the proton and neutron targets , based on quark model calculation. Quark-hadron duality for the nucleon spin structure function is also analyzed. Effects of the Δ(1232) and Roper P11(1440) resonances on the spin structure function and on the difference are mentioned. The results of different models for the Roper resonance are also addressed.

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

We derive the exchange currents of pseudoscalar, vector, and scalar mesons from Feynman diagrams, and use them to calculate the magnetic form factors of nucleon and △(1232). The magnetic moments and electromagnetic radii are obtained by using those form factors and the parameters determined from the masses of nucleon and △(1232).We find the magnetic moments and electromagnetic radii of nucleon and △(1232) can be produced very well in the extended Goldstone-Boson-exchange model in which all of pseudoscalar, vector, and scalar meson nonet are included.The magnetic moments of △(1232) are closer to experiment values and results from lattice calculation than the results obtained by the model without other mesons except for pion and sigma.

Bloom-Gilman Duality of Nucleon Spin Structure Function and Elastic Peak Contribution

By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-hadron duality of g_1 both in the inelastic resonanceregion and elastic one.

Probing the medium effect and isospin dependence of the in-medium nucleon-nucleon cross section in heavy ion collisions

Probing in-medium nucleon-nucleon （NN） cross section σ1/NN（α） in heavy ion collisions has been investigated by means of the isospin-dependent quantum molecular dynamics （IQMD） with the isospin- and momentum-dependent interaction （IMDI（T））. It is found that there are the very obvious medium effect and the sensitive isospin-dependence of nuclear stopping R on the in-medium NN cross section α1/NN（α） in the nuclear reactions induced by halo-neutron projectile and the same-mass stable projectile. However, R induced by the neutron-halo projectile is obviously lower than that induced by the corresponding stable projectile. In particular, there is a very obvious dependence of R on the medium effect of σ1/NN（α） in the whole beam energy region for the above two kinds of projectiles. Therefore, the comparison between the results of R＇s in the reactions induced by the neutron-halo projectile and the corresponding same-mass stable projectile is a more favourable probe for extracting the information of σ1/NN（α） because of adding a new judgement.

Nucleon Form Factors and N-△ Transitions in a Hypercentral Constituent Quark Model with Meson Cloud

We study the nucleon form factors and the nucleon-△（1232） transitions in a framework of hypercentral constituent quark model. The pion meson cloud effect is taken into account explicitly. Our results show that the pion cloud contributes substantially to the nucleon form factors as well as to the helicity amplitudes of △（1232）, and it gives an improved agreement compared to the experimental.