Axial form-factor and induced pseudoscalar form-factor of the nucleons

In this article, we calculate the axial and the induced pseudoscalar form-factors $G_A(t=-Q^2)$ and $G_P(t=-Q^2)$ of the nucleons in the framework of the light-cone QCD sum-rules approach up to twist-6 three valence quark light-cone distribution amplitudes, and observe that the form-factors $G_A(t=-Q^2)$ and $G_P(t=-Q^2)$ at intermediate and large momentum transfers with $Q^2> 2 GeV^2$ have significant contributions from the end-point (soft) terms. The numerical values for the axial form-factor $G_A(t=-Q^2)$ are compatible with the experimental data and theoretical calculations, for example, the chiral quark models and lattice QCD. The numerical values for the induced pseudoscalar form-factor $G_P(t=-Q^2)$ are compatible with the calculation from the Bethe-Salpeter equation.Comment: 21 pages, 12 figures, revised versio

Extraction of the neutron charge form factor from the charge form factor of deuteron

We extract the neutron charge form factor from the charge form factor of deuteron obtained from $T_{20}(Q^2)$ data at $0\le Q^2\le$ 1.717 (GeV$^2$). The extraction is based on the relativistic impulse approximation in the instant form of the relativistic Hamiltonian dynamics. Our results (12 new points) are compatible with existing values of the neutron charge form factor of other authors. We propose a fit for the whole set (35 points) taking into account the data for the slope of the form factor at $Q^2 = 0$.Comment: LaTeX2e, 12 pages, 2 figures, tabl

Remarks on Form Factor Bounds

Improved model independent upper bounds on the weak transition form factors are derived using inclusive sum rules. Comparison of the new bounds with the old ones is made for the form factors h_{A_1} and h_V in B -> D* decays.Comment: 8 pages, 2 figures, title changed and typos corrected for journal publicatio

"Point-form" estimate of the pion form factor revisited

The pion form factor calculation in the ``point-form'' of relativistic quantum mechanics is re-considered. Particular attention is given to the relation between the momentum of the system and the momentum transfer as well as to the quark current.Comment: 3 pages, 2 figures, contribution to the 17th International IUAP Conference on Few-Body Problems in Physics, 5-10 June 2003, Durham (USA

Electromagnetic form factor of the pion

The Standard Model prediction for the magnetic moment of the muon requires a determination of the electromagnetic form factor of the pion at high precision. It is shown that the recent progress in pi-pi scattering allows us to obtain an accurate representation of this form factor on the basis of the data on e+e- -> pi+ pi-. The same method also applies to the form factor of the weak vector current, where the data on the decay tau -> pi- pi0 nu are relevant. Unfortunately, however, the known sources of isospin breaking do not explain the difference between the two results. The discrepancy implies that the Standard Model prediction for the magnetic moment of the muon is currently subject to a large uncertainty. Talk given in May 2002, in honor of Arkady Vainshtein.Comment: Talk given at the Workshop "Continuous Advances in QCD 2002/Arkadyfest", Minneapolis, May 2002, 19 p

QCD Constraints on Form Factor Shapes

This talk presents an introduction to the use of dispersion relations to constrain the shapes of hadronic form factors consistent with QCD. The applications described include methods for studying |V_{cb}| and |V_{ub}|, the strange quark mass, and the pion charge radius.Comment: 8 pages, 3 eps figures, presented at ``Exclusive & Semi-exclusive Processes at High Momentum Transfer,'' Jefferson Lab, Newport News, VA, May 20-22, 199