Nucleon-nucleon interaction with tensor forces in the quark compound bag model

A model forN-N interaction proposed earlier by two of us (VSB and VKG), has been extended to incorporate the tensor component of the nuclear force. Based on the quark compound bag model (QCB), the nucleon-nucleon potential has a short range repulsive core which is non-local and has a characteristic energy dependence and is expressed in terms of the parameters relating to the six-quark compound bag. To account for the low energy properties, this repulsive core interaction is supplemented by a phenomenological non-local potential containing both central (S-wave) and tensor components and operates only outside the QCB. Using this model, we analyse and compare the results with the experimental data for the electromagnetic form factors of the deuteron, theD-state observables, such as the quadrupole moment, theD-state probability, and theD/S ratio along with then-p scattering phase shifts up to about 400 MeV.     

1S0 and 3S13D1 nucleon-nucleon potentials in the quark compound bag model

For nucleons interacting via formation of the quark compound bag the resulting potential is written in a general form. Explicit examples of potentials are constructed in the ¹S₀, ³S₁ and ³S₁-³D₁ states fitted to the experimental data at T_L ? 1 GeV. As an outcome the QCB energy levels (dibaryons) and NN admixture in QCB are obtained in good agreement with theoretical predictions.     

Nuclear chromodynamics and the six-quark compound bag component of the deuteron

Based upon a new formulation of nuclear chromodynamics, we determine the probability of the six-quark compound bag component of deuteron to be 2.2–5.5% using the experimental np partial width of the dibaryon resonance of Kamae et al.     

Effects of six-quark bags on the1 D 2 NN partial wave and the question of dibaryon resonances

The coupled¹ D ₂(pp)?⁵ S ₂ (ΔN) channels are studied in a relativized version of the Quark Compound Bag (QCB) model. The QCB short-range force is shown to reproduce an, energy dependence of the¹ D ₂ phase shift and inelasticity atT?200MeV predicted by the energy-independent solution of the VPISU phase-shift analysis. At lower energy the effect of the long-range meson force is essential. The values of the QCB parameters found from the fit to the data are in good agreement with theoretical predictions for the MIT bag model.     

Polarization in elastic eD-scattering at large transfer momenta and quark structure of the deuteron

It is shown that a small (5–8)% admixture of the six-quark component in the deuteron wave function which is to be introduced to describe elastic eD-scattering at large transfer momenta changes essentially the behaviour of the polarization tensorT ₂₀ and the ratioR of the vectorP _x to tensor polarizationP _xz compared to the models which do not take such admixtures into account. The corresponding experiments are emphasized to be important, which are aimed at testing the predictions of models including six-quark admixtures in the deuteron.     

Form factors and polarization in the elasticeD-scattering with inclusion of meson and quark degrees of freedom in a deuteron

A detailed analysis is made of the pair,ρπγ-currents, retardation effects and six-quark admixtures to the charge, quadrupole form factors and to the deuteron polarization. It is shown that the elasticeD-scattering cross section allowing for the meson exchange currents can be described by introducing a six-quark admixture with probability 3.5%. It is predicted that the behaviour of the deuteron polarization tensor at q>4 fm^?1 essentially depends on 6q-admixture.     

The six-quark-admixture in the form factor of the3He at large transfer momenta

Elastic form factor of the³He nucleus is analysed with the use of Gaussian-type and realistic nuclear wave functions with a contribution of six-quark admixtures taken into account. The latter has been chosen so as to describe the data of analysis of cumulative and other processes and it amounts to about 8%. It is shown that unlike the deuteron form factor for³He the quark-nucleon interference is essential. The six-quark admixture does not remove the second minimum in the form factor of³He as a three-nucleon system atq ²~50 fm^?2. The comparison with other theoretical models and available experimental data is performed.     

High momentum component in the deuteron

The high momentum component in the deuteron, which stems from the short range part of the nucleon-nucleon interaction, is studied in they-scaling function and the structure functionF ₂ of the deuteron. We use not only some non-relativistic wave functions but also relativistic ones. It is shown that the relativistic mechanism or a six-quark state in the nucleon-nucleon interaction yields a large high momentum component.     

n ↔ n transition operators and their matrix elements in the MIT bag model

We give the general set of six-quark operators which can contribute to n ? $\text{n}$ transitions and calculate their matrix elements, using the MIT bag model.     

Six-quark effects in the proton-deuteron break-up reaction

The impulse-approximation model has been used to analyse spectator momentum distributions in dp → pnp reaction with deuterons of 3.3 GeV/c momentum incident on a hydrogen bubble chamber. The model includes corrections due to (i) final-state interactions between the two slow nucleons, (ii) double scattering (shadowing), and (iii) six-quark effects modifying the deuteron (Paris) wave function. The six-quark correction is obtained by eliminating Pauli-forbidden components from the deuteron wave function. The overall agreement with experiment is very good. We find the six-quark correction indispensable for reproducing the high-momentum tail of the spectator momentum distribution.     

Quark recombination in deuteron fragmentation

Low-P _T production off deuteron in the fragmentation region is studied on the basis of a six-quark picture of deuteron. It is argued that all the six valence quarks participate equally in the hadronization processes associated with meson and baryon productions. Thex-distribution of the inclusive cross sections is studied in the framework of a quark recombination model. Fit with experimental data leads to a determination of the valence and sea quark distributions in deuteron. Probabilistic arguments applied to a general recombination picture are shown to lead to some experimentally verifiable constraints on baryon multiplicities. Possibilities of determining the various recombination probabilities are also discussed.     

Dibaryon Concept for Short-Range 2N and 3N Forces: Consequences for Hadronic and Nuclear Physics

The short-range aspects of 2N and 3N nuclear interactions are considered in light of numerous novel experimental data obtained in JLab, BNL, Mainz, etc. Many of these new experimental results contradict strongly to the traditional models for short-range (or high-momentum) components of nuclear forces and therefore require a novel understanding within new models alternative to the traditional (one-boson-exchange) ones. At the NN distances r _{N N} < 1 fm the nucleon quark cores get overlapped with each other and thus the generation of the common six-quark bag is very likely. So, the dibaryon concept considers the generation of the intermediate six-quark bag dressed with meson (predominantly the scalar-isoscalar σ-meson) clouds as a driving mechanism for short-range nuclear force. Numerous predictions of the above dibaryon model are considered in the paper.     

Pionic and radiative decays of vector mesons in the chiral bag model

It is shown that a mechanism, within the framework of the cloudy bag model, analogous to that fore ⁺ e ^?→2ψ in QED accounts qualitatively for the decays ?→2π, ω→πψ and ?→πψ with a bag radii 0.8–1.0 fm, and averaged momenta for decay particles. For the radiative decays, the process identical to that in the vector-dominance model gives about 60% of the total calculated width. It also explains small decay widths previously calculated, using the single quark transition process.     

The pomeron colour structure and hadron scattering on the six-quark deuteron configuration

The pomeron colour structure provides some contribution to the elastic hadron-deuteron amplitude not contained in the Glauber like approach. This contribution is very sensitive to the short distance behaviour of the deuteron wave function and poses one to fix with a high precision a size of the deuteron six-quark bag.     

Calculation of the hyperfine structure of the 42 S 1/2, 42 P 1/2, 42 P 3/2 states in the 3d 10 nl configuration of Cu

The hyperfine structure of the 4² S _1/2, 4² P _1/2, 4² P _3/2 states in the 3d ¹⁰ nl configuration of Cu has been evaluated using many-body perturbation theory. Polarisation effects were included in all orders and correlation to third-order. By the use of iteration methods, a large number of higher order diagrams were also included. The correlation effects between the valence electron and the 3d shell were found to be very important. The results forA(² S _1/2) andA(² P _1/2) 5827MHz and 440 MHz, respectively, are in good agreement with the experimental results, whereas the result forA(² P _3/2)=83 MHz is far from the experimental value. No explanation was found for the discrepancy. The quadrupole values were found to be ?206 mb for⁶³Cu and ?185 mb for⁶⁵Cu.     

The ABC effect and chiral-bag-model form factors

We investigate the ABC effect in the reaction n+p → d+(ππ)⁰ using the chiral lagrangian of Weinberg in the tree approximation. Chiral-bag-model form factors are used for the vertices. We obtain cross sections as a function of energy for deuteron scattering angles θ_d = 0° and 10.5°. The results are compared with the latest experimental measurements. The fit to the absolute value of the cross section is obtained taking the bag radius R as a free parameter; the fitted value of R turns out to be that expected in the light of previous studies in the framework of chiral bag models. The ABC effect is almost completely accounted for in terms of the lowest-order diagrams.     

Intense deuteron beam investigation by activation yield-ratio technique

In this work, the intense deuteron beam from a plasma focus device is investigated by the activation yield-ratio technique. It is shown that boron-carbide (B₄C) and boron-nitride (BN) are complimentary targets for high energy deuteron beam studies. For deuteron spectra of the form dNd/dE∝E−n, when deuteron spectra decrease relatively gradually (n<6) BN is a better choice, while for the case of very rapidly decreasing deuteron spectra (n>6), B₄C is more suitable.     

The quark configurationsS 6 andS 4 P 2 in the bag model

The spectrum and eigenfunctions of deuteronlike states in the quark bag for the configurationsS ⁶ andS ⁴ P ² have been studied. The complete tables of the fractional parentage coefficients (f.p.c.) for these configurations in thej-j andL-S coupling schemes are presented. The universal method of calculation of the f.p.c. which is based on the complementarity of the unitary and permutation group, is considered. The method enable one to calculate the Clebsh-Gordon coefficients and the invariant symbols of the noted groups. It is shown that the lowest energy state of the configurationS ₁ ^2/4 P ₃ ^2/2 resembles the partial wave³ D ₁ and can, therefore, be coupled to it in a deuteron. On the contrary, the lowest states in the configurationsS ₁ ^2/6 andS ₁ ^2/4 P ₁ ^2/2 resemble the³ S ₁-wave.     

The deuteron wave function at short range and the triton

It is shown that if one assumes something between zero and the prediction of the scaling model with dipole fit for the neutron electric form factor, then a variety of short-range behaviour for the deuteron wave function is consistent with existing experimental data on the deuteron electric form factor. This still relatively wide latitude for the inner deuteron wave function, consistent with existing experimental electromagnetic data, gives rise to an off-shell variation of approximately 1.2 MeV in the triton binding energy with a fixed ¹S₀ interaction and a P_D varying from 4.5 to 6.5 %. Interactions with greater densities of matter at short range bind the triton more strongly and closer to the experimental value. An off-shell variation of 0.7 MeV is obtained with a fixed p_d and singlet interaction. However, a single measurement of the deuteron tensor polarization at about q² = 20 fm^?2 would severely restrict this variation.