Related papers: A Model for the Pion Structure Function
We analyzed two twist-3 distribution amplitudes of pion, i.e. pseudoscalar $\phi^P_{3;\pi}(x)$ and pseudotensor $\phi^\sigma_{3;\pi}(x)$, within the LFQM. Our LFQM descriptions both for twist-3 $\phi^P_{3;\pi}$ and $\phi^\sigma_{3;\pi}$ not…
The common view that structure functions measured in deep inelastic lepton scattering are determined by the probability of finding quarks and gluons in the target is not correct in gauge theory. We show that gluon exchange between the fast,…
Using a holographic dual model of QCD, we compute the pion electromagnetic form factor F_pi(Q^2) in the spacelike momentum transfer region, as well as pion couplings to vector mesons g_rho^(n) pi pi. Spontaneous and explicit chiral symmetry…
The recent unbiased measurements of the electric form factor of the neutron suggest that its shape may be interpreted as a smooth broad distribution with a bump at Q^2 \approx 0.3(GeV/c)^2 superimposed. As a consequence the corresponding…
The evolution of the pion distribution amplitude in next-to-leading order is studied for a fixed and a running coupling constant. In both cases, the evolution provides a logarithmic modification in the endpoint region. Assuming a simple…
We study the form factors of the quark tensor currents in the pion at large squared momentum transfer Q^2. It turns out that certain form factors can be evaluated using collinear factorization, whereas others receive important contributions…
We study the structure of the sigma meson, the lowest-lying resonance of the pi pi scattering in the scalar-isoscalar channel, through the softening phenomena associated with the partial restoration of chiral symmetry. We build dynamical…
We present an exploratory calculation of the $I=2$ $\pi-\pi$ scattering amplitude at threshold using Wilson fermions in the quenched approximation, including all the required contractions. We find good agreement with the predictions of…
The Vector Pion form factor below 1 GeV is analyzed using experimental data on its modulus, the P-wave pion pion phase shifts and dispersion relation. It is found that causality is satisfied. Using dispersion relation, terms proportional to…
Exclusive two-pion production near threshold in the collision of a highly virtual photon with a real one offers a new possibility to unravel the partonic content of hadrons. We explain the dynamics of this regime, i.e. the separation of the…
The b1 structure function is an observable feature of a spin-1 system sensitive to non-nucleonic components of the target nuclear wave function. The contributions of exchanged pions in the deuteron are estimated and found to be of…
The parton distribution function of the pion in the valence region is extracted in a next-to-leading order analysis from Fermilab E-615 pionic Drell-Yan data. The effects of the parameterization of the pion's valence distributions are…
We compare the dependences on the number of colors of the leading pion pion scattering amplitudes using the single index quark field and two index quark fields. These are seen to have different relationships to the scattering amplitudes…
The invariant amplitudes for pion electroproduction on the nucleon are evaluated by dispersion relations at constant t with MAID as input for the imaginary parts of these amplitudes. In the threshold region these amplitudes are confronted…
We use the transverse-momentum dependence of the cross section for diffractive dissociation of high energy pions to two jets to study some non-perturbative Light-Cone wave functions of the pion. We compare the predictions for this…
This work discusses the approximations frequently used to calculate the contribution to pion production in proton-proton scattering near threshold from irreducible pion re-scattering. The reference result is obtained from the quantum…
Results of the Spectral Quark Model for the gravitational, electromagnetic, and transition form factors of the pion are discussed. In this model both the parton distribution amplitude and the parton distribution function are flat, in…
We discuss aspects of a covariant QCD modeling of meson physics by illustrating applications to several coupling constants and form factors. In particular, we cover the $\rho\pi\pi$ and $\pi^0 \gamma \gamma$ interactions, the $\rho$…
Deep inelastic polarized and unpolarized structure functions for a free nucleon are obtained in a modified Center-of-Mass bag model, which includes the symmetry breaking effects from spin-dependent interactions. The quark distribution…
The spin structure of the proton is investigated in the framework of an extended quark potential model which in addition to the conventional $3q$--structure also takes into account $(3q)(q\bar q)$--admixtures in the proton wave function.…