نتایج جستجو برای: electromagnetic form factor
تعداد نتایج: 1546779 فیلتر نتایج به سال:
We study the largeQ 2 behavior of the electromagnetic form factor of the pion, which is viewed as a quarkantiquark bound state in a (nongauge) quantum field theory. When the pion's Bethe-Salpeter wave function is expanded in 0(4) partial waves, it is found that the information needed about the partial-wave amplitudes is their scaling behavior at large momentum and the locations of their poles i...
We discuss two applications of the Virtuality Distribution Amplitudes (VDA) formalism developed in our recent papers. We start with an overview of the main properties of the pion distribution amplitude emphasizing the quantitative measures of its width, and possibility to access them through the pion transition form factor studies. We formulate the basic concepts of the VDA approach and introdu...
Based on the light-cone (LC) framework and the kT factorization formalism, the transverse momentum effects and the different helicity components’ contributions to the pion form factor Fπ(Q) are recalculated. In particular, the contribution to the pion form factor from the higher helicity components (λ1 + λ2 = ±1), which come from the spinspace Wigner rotation, are analyzed in the soft and hard ...
The electromagnetic pion form factor, Fπ(q 2), is calculated for spacelike-q2 in impulse approximation using a confining quark propagator, S, and a dressed quarkphoton vertex, Γμ, obtained from realistic, nonperturbative Dyson-Schwinger equation studies. Good agreement with the available data is obtained for Fπ(q 2) and other pion observables, including the decay π0 → γ γ. This calculation sugg...
The pion form factor is computed using quenched twisted mass QCD and the GMRES-DR matrix inverter. The momentum averaging procedure of Frezzotti and Rossi is used to remove leading lattice spacing artifacts, and numerical results for the form factor show the expected improvement with respect to the standard Wilson action. Although some matrix inverters are known to fail when applied to twisted ...
The suggestion of momentum dependence in the amplitude for rho-omega mixing has generated concern over related implications for vector meson dominance and the photon-rho coupling. We discuss two established representations of vector meson dominance and show that one of these is completely consistent with such a coupling. We then apply it to a calculation of the pion electromagnetic form-factor....
Separated longitudinal and transverse structure functions for the reaction 1H(e,e(')pi(+))n were measured in the momentum transfer region Q2 = 0.6--1.6 (GeV/c)(2) at a value of the invariant mass W = 1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in ...
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