1202.0734 (J. P. B. C. de Melo et al.)

Light-Front projection of spin-1 electromagnetic current and zero-modes    [PDF]

J. P. B. C. de Melo, T. Frederico

The issue of the contribution of zero-modes to the light-front projection of
the electromagnetic current of phenomenological models of vector particles
vertices is addressed in the Drell-Yan frame. Our analytical model of the
Bethe-Salpeter amplitude of a spin-1 fermion-antifermion composite state gives
a physically motivated light-front wave function symmetric by the exchange of
the fermion and antifermion, as in the $\rho$-meson case. We found that among
the four independent matrix elements of the plus component in the light-front
helicity basis only the $0\to 0$ one carries zero mode contributions. Our
derivation generalizes to symmetric models, important for applications, the
above conclusion found for a simplified non-symmetrical form of the spin-1
Bethe-Salpeter amplitude with photon-fermion point-like coupling and also for a
smeared fermion-photon vertex model.

View original: http://arxiv.org/abs/1202.0734