Strong nucleon and Δ-isobar form factors in the quark-confinement model

The nucleon and the -isobar are investigated as three-quark systems in the quark-confinement model (QCM). This model is based on two hypotheses. First, quark confinement is accomplished through averaging over some vacuum gluon fields which are assumed to provide the confinement of any colour states. Second, hadrons are treated as collective colourless excitations of quark-gluon interactions.The QCM is applied to low-energy baryon physics. The nucleon magnetic moments and electromagnetic radii, the ratioG _A /G _V , and the decay width for p are calculated. The behaviour of the electromagnetic and strong mesonnucleon (meson-isobar) form factors is determined for space-like momentum transfers. The results are compared with experimental data for the electromagnetic form factors and phenomenological strong form factors as used in the Bonn potential.     

Strangeness in the nucleon: neutrino–nucleon and polarized electron–nucleon scattering

After the EMC and subsequent experiments at CERN, SLAC and DESY on the deep inelastic scattering of polarized leptons on polarized nucleons, it is now established that the Q²=0 value of the axial strange form factor of the nucleon, a quantity which is connected with the spin of the proton and is quite relevant from the theoretical point of view, is relatively large.In this review, we consider different methods and observables that allow one to obtain information on the strange axial and vector form factors of the nucleon at different values of Q². These methods are based on the investigation of the neutral current induced effects such as the P-odd asymmetry in the scattering of polarized electrons on protons and nuclei, the elastic neutrino (antineutrino) scattering on protons and the quasi-elastic neutrino (antineutrino) scattering on nuclei. We discuss in detail the phenomenology of these processes and the existing experimental data.     

Relation between the charged and neutral pion–nucleon coupling constants in the Yukawa model

In the Yukawa-model framework for NN forces, a simple relation between the charged and neutral pion–nucleon coupling constants is derived. The relation implies that the charged pion–nucleon constant is larger than the neutral one since the np interaction is stronger than the pp interaction. The derived value of the charged pion–nucleon constant shows a very good agreement with one of the recent measurements. In relative units, the splitting between the charged and neutral pion–nucleon constants is predicted to be practically the same as that between the charged and neutral pion masses. The charge dependence of the NN scattering length arising from the mass difference between the charged and neutral pions is also analyzed.     

Systematic comparison of barriers for heavy-ion fusion calculated on the basis of the double-folding model by employing two versions of nucleon–nucleon interaction

A systematic calculation of barriers for heavy-ion fusion was performed on the basis of the double-folding model by employing two versions of an effective nucleon–nucleon interaction: M3Y interaction and Migdal interaction. The results of calculations by the Hartree–Fockmethod with the SKX coefficients were taken for nuclear densities. The calculations reveal that the fusion barrier is higher in the case of employing theMigdal interaction than in the case of employing the М3Y interaction. In view of this, the use of the Migdal interaction in describing heavy-ion fusion is questionable.     

Qweak, N → Δ, and physics beyond the standard model

The data-taking phase of the Qweak experiment ended in May of 2012 at the Thomas Jefferson National Accelerator Facility. Qweak aims to measure the weak charge of the proton, Q _W ^p , via parity-violating elastic electron-proton scattering. The expected value of Q _W ^p is fortuitously suppressed, which leads to an increased sensitivity to physics beyond the Standard Model.     

Δ Isobar decay in covariant quark model

We investigate the strong decay of the isobar in the covariant quark model. The detailed derivation of the relativistic three-quark current with the quantum numbers \({J^P} = \frac{3}{2}^{+}\) is given. It is shown that this current has a unique form. The decay width is calculated by fitting the free parameter of the model. The behavior of the strong form factor G_Δpπ(Q²)for spacelike squared transferred pion momentum is obtained.     

A covariant representation of the Ball–Chiu vertex

In nonabelian gauge theory the three-gluon vertex function contains important structural information, in particular on infrared divergences, and is also an essential ingredient in the Schwinger–Dyson equations. Much effort has gone into analyzing its general structure, and at the one-loop level also a number of explicit computations have been done, using various approaches. Here we use the string-inspired formalism to unify the calculations of the scalar, spinor and gluon loop contributions to the one-loop vertex, leading to an extremely compact representation in all cases. The vertex is computed fully off-shell and in dimensionally continued form, so that it can be used as a building block for higher-loop calculations. We find that the Bern–Kosower loop replacement rules, originally derived for the on-shell case, hold off-shell as well. We explain the relation of the structure of this representation to the low-energy effective action, and establish the precise connection with the standard Ball–Chiu decomposition of the vertex. This allows us also to predict that the vanishing of the completely antisymmetric coefficient function S   of this decomposition is not a one-loop accident, but persists at higher-loop orders. The sum rule found by Binger and Brodsky, which leads to the vanishing of the one-loop vertex in N=4$N=4$ SYM theory, in the present approach relates to worldline supersymmetry.     

On the nucleon–nucleon scattering phase shifts through supersymmetry and factorization

By exploiting the supersymmetry-inspired factorization method through a judicious use of deuteron ground state wave function, higher partial wave nucleon–nucleon potentials, both energy independent and energy dependent, are generated. We adopt the phase function method to deal with the scattering phase shifts and demonstrate the usefulness of our constructed potentials by means of model calculation.     

The Weiss model and the Landau–Khalatnikov model for the switching of ferroelectrics

It is shown that the molecular field theory by P. Weiss formally leads to the switching kinetics of ferroelectrics, which is described by the well-known Landau–Khalatnikov equation. The switching has a critical character, taking place only at E_a>E_c (E_a: external field, E_c: coercive field). The results are checked by computer simulations.     

A numerical scheme for the Green–Naghdi model

In this paper a hybrid numerical method using a Godunov type scheme is proposed to solve the Green–Naghdi model describing dispersive “shallow water” waves. The corresponding equations are rewritten in terms of new variables adapted for numerical studies. In particular, the numerical scheme preserves the dynamics of solitary waves. Some numerical results are shown and compared to exact and/or experimental ones in different and significant configurations. A dam-break problem and an impact problem where a liquid cylinder is falling to a rigid wall are solved numerically. This last configuration is also compared with experiments leading to a good qualitative agreement.     

A splitting approach for the fully nonlinear and weakly dispersive Green–Naghdi model

The fully nonlinear and weakly dispersive Green–Naghdi model for shallow water waves of large amplitude is studied. The original model is first recast under a new formulation more suitable for numerical resolution. An hybrid finite volume and finite difference splitting approach is then proposed, which could be adapted to many physical models that are dispersive corrections of hyperbolic systems. The hyperbolic part of the equations is handled with a high-order finite volume scheme allowing for breaking waves and dry areas. The dispersive part is treated with a classical finite difference approach. Extensive numerical validations are then performed in one horizontal dimension, relying both on analytical solutions and experimental data. The results show that our approach gives a good account of all the processes of wave transformation in coastal areas: shoaling, wave breaking and run-up.     

A simplest seesaw model of the TM1 and μ-τ reflection symmetries for the neutrino masses and leptogenesis

In this paper, following the Occam’s razor principle, we have put forward a very simple form of the Dirac neutrino mass matrix M_D in the minimal seesaw model with the right-handed neutrino mass matrix being diagonal M_R=diag(M₁,M₂); it has one texture zero and only contains three real parameters, whose values can be determined from the neutrino oscillation experimental results. Such a model leads to a neutrino mass matrix M_v? -M_DM<...