arXiv subjects

J. S. Veiga

Publications and source records attributed to J. S. Veiga.

2 recordsLinked to original sources

arXiv2006

Pole Approximation for the pion eletromagnetic form factor within light-front dynamics

We carefully investigate the reliability of the propagator Pole Approximation, i.e, the approximation of retaining only the propagator in the evaluation of the Mandelstam covariant expression for the eletromagnetic current of the pion. Different frames are analyzed, in order to find the most suitable one for calculating the pion form factor within the proposed approximation. It turns out that approximation is more accurate in the frame where q^+ is maximal. The relevance of the Pole Approximation is briefly discussed in view of calculations of hadrons factors basead wave functions generate by dynamical models.

hep-ph↗

arXiv2000

The Nucleon Anapole Form Factor in Chiral Perturbation Theory to Sub-leading Order

The anapole form factor of the nucleon is calculated in chiral perturbation theory to sub-leading order. This is the lowest order in which the isovector anapole form factor does not vanish. The anapole moment depends on counterterms that reflect short-range dynamics, but the momentum dependence or the form factor is determined by pion loops in terms of parameters that could in principle be fixed from other processes. If these parameters are assumed to have natural size, the sub-leading corrections do not exceed ~ 30% at momentum Q ~ 300 MeV.

hep-ph↗