Narrow Results

We introduce the form factor and short range correlation in the relativistic Hartree-Fock approximation (RHFU) to study the properties of nuclear matter. We treat the short range correlation with the unitary correlation operator method (UCOM). In this framework, we can perfectly reproduce the equation of state of pure neutron matter obtained by the relativistic Brueckner-Hartree-Fock theory with the Bonn potential. We apply the RHFU model to symmetric nuclear matter. The contribution of ρ meson is cut down largely by the form factor of the size in the realistic nucleon-nucleon interaction. The short range correlation has a significant effect on the Fock energies of pion and ρ meson exchange interaction.

The main features of obtaining the asymptotic behavior of the electric structure function $A(p)$ at large values of the transmitted momentum are analyzed. The asymptotic behavior of the structure function $A(p)$ was determined to take into account the asymptotic behavior of the deuteron form factors and the original dipole approximation for the nucleon form factors. Asymptotic values of $A(p)$ were obtained for the nucleon–nucleon potential Reid93 and compared with the calculations for different nucleon form factor models and their approximations. In the broad momentum range up to 12.5 fm${}^{-1}$, the basic forms of the asymptotic behavior of the electric structure function are demonstrated and compared with the experimental data of the modern collaborations. As the analysis shows in most cases considered, the asymptotic for $A(p)$ is represented in the form of the power function $p^{-n}$.

The noncommutative dipole QED is studied in detail for the matter fields in the adjoint representation. The axial anomaly of this theory is calculated in two and four dimensions using various regularization methods. The Ward–Takahashi identity is proved by making use of a nonperturbative path integral method. The one-loop β-function of the theory is calculated explicitly. It turns out that the value of the β-function depends on the direction of the dipole length L, which defines the noncommutativity. Finally using a semiclassical approximation a nonperturbative definition of the form factors is presented and the anomalous magnetic moment of this theory at one-loop order is computed.

We present a study of D⁰ decaying to K^-ℓ⁺ν and π^-ℓ⁺ν final states using a 282 fb^-1 data sample collected by the Belle experiment at the KEKB e⁺e^- collider. The D⁰ flavor and momentum are tagged through a full reconstruction of the recoiling charm meson and additional mesons from fragmentation. The reconstruction method provides very good resolution in neutrino momentum and in q² = (p_ℓ + p_ν)². Normalizing to the total number of D⁰ tags, we measure the absolute branching fractions to be and and the semi-leptonic form factors (within the modified pole model) and .

Based on 14 M ψ′ events, systematic studies have been make for hadronic decays, which are conerned with 12% rule test, phase analysis and form factor measurement. All these studies are helpful for understanding the decay dynamics in charmonium region.

The diquark structure in baryons is commonly accepted as a reasonable approximation which can much simplify the picture of baryons and reduce the length of calculations. However, a diquark by no means is a point-like particle, even though it is treated as a whole object. Therefore, to apply the diquark picture to phenomenological calculations, at the effective vertices for the diquark–gauge-boson interactions, suitable form factors must be introduced to compensate the effects caused by the inner structure of the diquark. It is crucial to derive the appropriate form factors for various interactions. In this work, we use the Bethe–Salpeter equation to derive such form factors and numerically evaluate their magnitudes. Our results not only qualitatively, but also quantitatively confirm the form factors phenomenologically introduced in literature.

In October 2008, the WASA-at-COSY collected more than 10⁷ events for the pd → ³Heη reaction. The aim is the determination of the invariant mass of the lepton pairs created in the Dalitz decay η → γe⁺e^-. The e⁺e^- invariant mass spectrum is directly related to the distribution of the four-momentum squared of the virtual photon from the η → γγ* process and hence it allows for the study of the transition form factor which in turn reflects the structure of the decaying meson.

In this paper, we calculate the proton and neutron unpolarized and transversely polarized densities. We use the light-front wave function (LFWF), which at an initial scale is constrained by the soft-wall anti-de Sitter (AdS) QCD model, for calculating the Dirac and Pauli form factors which transverse densities are in terms of these form factors. Also, we use these form factors for calculating the flavor separated results for the proton and neutron electromagnetic form factors and calculate u and d quark unpolarized and transversely polarized densities. Finally, we compare our results with other previous parametrizations.

By using the AdS/CFT correspondence, we investigate various form factors between nucleons and mesons in a nuclear medium. In order to describe a nuclear medium holographically, we take into account the thermal charged AdS geometry with an appropriate IR cutoff. After introducing an anomalous dimension as a free parameter, we investigate how the nucleon’s mass is affected by the change of the anomalous dimension. Moreover, we study how the form factors of nucleons rely on the properties of the nuclear medium. We show that in a nuclear medium with different numbers of proton and neutron, the degenerated nucleon form factor in the vacuum is split into four different values depending on the isospin charges of nucleon and meson.

The goal of this paper is to extract the flavor decomposition of nucleon electromagnetic form factor using the modified Gaussian and extended Regge ansatzes in the GPDs. We consider the CJ15 and JR09 parton distribution functions for both of these ansatzes in calculating the nucleon elastic form factors. Our results are compared with experimental data in the range $0<-t<4.5{\mathrm{\text{GeV}}}^2$ 4-momentum transfers. Also, we calculate the total angular momentum carried by quarks, the gravitational form factors, and the transverse gravitational density for quarks of the nucleon. In the end, our results are compared with the other studies.

We investigate the electromagnetic form factor of $D_s^{\ast }$ meson using $N_f=2$ twisted mass lattice quantum chromodynamics gauge configurations. The numerical simulations are carried out under twisted boundary conditions which are helpful to increase the resolution in momentum space. We determine electromagnetic form factors with more small four-momentum transfer, and further fit the charge radius for $D_s^{\ast }$ meson.

The NA48/2 experiment at CERN reports the first observation of the $K^{\pm }\to {\pi }^{\pm }{\pi }^0{e}^{+}{e}^{-}$ decay from an exposure of $1.7\times 10^{11}$ charged kaon decays recorded in 2003–2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region. The study of the kinematic space shows evidence for a structure-dependent contribution in agreement with predictions based on chiral perturbation theory. Several $P$- and $CP$-violating asymmetries are also evaluated. The most precise measurement of the charged kaon semi-leptonic form factors obtained by NA48/2 with 4.4 million $K_{e3}$ and 2.3 million $K_{\mu 3}$ events collected in 2004 will also be presented.

The axial-vector form factor of the nucleons is studied at a finite temperature using the holographic soft-wall model with the thermal dilaton field. We use the bulk interaction action known from the zero temperature case and apply the profile functions of fields thermalized by the interaction with the thermal dilaton field. The dependence of the axial form factor on the square of the transferred momentum and the temperature is plotted for the ground and excited states of the nucleons.

One of the primary, but tedious, tasks for the user and developer of an optical 3D-measurement system is to find the homologous image points in multiple images, a task that is frequently referred to as the correspondence problem. Along with the solution, error-free correspondence and accurate measurement of image points are of great importance, on which the qualitative results of succeeding camera calibration and 3D-measurements are immediately dependent. In fact, the automation of measurement processes is getting more important with progresses in production, and hence, is of increasing topical interest. In this paper, we present a circular coded target for automatic image point measurement and identification. The applied image processing method will be described in detail, and we will show some application examples of the circular coded target to optical 3D-measurement techniques.

The differential cross-sections for elastic ¹²C–¹²C scattering at 2400 and 1449 MeV are calculated on the basis of the multiple diffraction scattering theory and α-cluster model with dispersion. At the energy 2400 MeV the calculations were performed by means of "effective" and "free" α–α amplitudes. It is shown that the results obtained differ significantly.

The form factor of the transition ργ*→π⁰ is investigated by analyzing the γγ*→π⁰ transition in the framework of the light-cone local duality quantum chromodynamics sum rules. Both finite- and zero-width forms for the low-energy physical absorptive part of the γγ*→π⁰ transition are considered. The numerical results for the transition form factor F^ρπ(Q²) in the asymptotic form and the CZ one of the pion distribution amplitude are obtained respectively, the difference between the finite- and zero-width form is not big but still distinguishable. It is found that the results for the form factor F^ρπ(Q²) from CZ, asymptotic and the flat pion DAs are compatible with the predictions of perturbative QCD. Our results will be helpful to distinguish the shape of the pion DA of twist-two, when the concrete information of the experimental data for the transition ργ*→π⁰ are provided.

Inelastic electron scattering form factors for ²⁹Si nucleus with total angular momentum and positive parity (J^π) and excited energy (3/2⁺, 1.273 MeV; 5/2⁺, 2.028 MeV; 3/2⁺, 2.425 MeV and 7/2⁺, 4.079 MeV) have been calculated using higher energy configurations outside the sd-shell. The calculations of inelastic form factors up to the first- and second-order with and without core-polarization (CP) effects were compared with the available experimental data. The calculations of inelastic electron scattering form factors up to the first-order with CP effects are in agreement with the experimental data, excepted for states 3/2⁺(1.273 MeV) and 5/2⁺(2.028 MeV) and without this effect are failed for all states. Furthermore, the calculations of inelastic electron scattering form factors up to the second-order with CP effects are in agreement with the experimental data for 3/2⁺(1.273 MeV) and 5/2⁺(2.028 MeV).

In this paper, inelastic longitudinal electron scattering form factors for C2 transition have been studied in ⁵⁴Fe and ⁵⁶Fe with the aid of shell model calculations. The GX1 effective interaction for the fp-shell is used with the nucleon–nucleon realistic interaction Michigan three-range Yukawa and Modified surface delta interaction as a two-body interactions. The core polarization effects is taken into account through the first-order perturbation theory with the effective charge, which is taken to the proton and the neutron. The effective charge along with the core effects up to 6 ℏw enhanced the calculation very well and improving good agreement with the experimental data.

In this paper, we discuss the charge and magnetization densities for proton and neutron in the transverse plane, whereas there are links between the generalized parton distributions (GPDs) and elastic form factors by means of sum rules. We use the extended Regge parameterization for large momentum transfer region for calculating Dirac and Pauli form factors which have been described in the electromagnetic form factors data, so we want to calculate the charge and magnetization densities for proton and neutron in the transverse plane and we also calculate $u$ and $d$ quark charge and magnetization densities. The extracted results are compared with other previous parameterizations.

Using the field-theory-inspired expression for the pion electromagnetic form factor F_π, a good description of the data in the range -10 < s < 1 GeV² is obtained upon taking into account the pseudoscalar-pseudoscalar (PP) loops. When the vector-pseudoscalar (VP) and the axial vector-pseudoscalar (AP) loops are taken into account in addition to the PP ones, a good description of the BABAR data on the reaction e⁺e⁻ → π⁺π⁻ is obtained at energies up to 3 GeV. The inclusion of the VP and AP loops demands the treatment of the reactions e⁺e⁻ → ωπ⁰ and e⁺e⁻ → π⁺π⁻π⁺π⁻. This task is performed with the SND data on ωπ⁰ production and the BABAR data on π⁺π⁻π⁺π⁻ production, both in e⁺e⁻ annihilation, by taking into account ρ(770) and the heavier ρ(1450), ρ(1700), and ρ(2100) resonances. The problems arising from including of the VP and AP loops are pointed out and discussed.