General angular conditions in light‐front dynamics for few‐body systems Available to Purchase

The light‐front dynamics(LFD) plays an important role in the analyses of few‐body systems as evidenced from the recent phenomenology covering both inclusive and exclusive processes. We thus discuss a few fundamental issues of LFD that should be taken into account for the phenomenological applications. In particular, we derive general angular conditions which should be satisfied by the light‐front helicity amplitudes for any spin system and obtain the light‐front parity and time‐reversal relations for the light‐front helicity amplitudes. As an application of these relations, we make some comments on the consequences of the general angular condition for the transition between spin‐1/2 and spin‐3/2 systems and find a relation useful for the analysis of the N‐Δ transition form factors. Also, for the analysis of the deuteron and ρ meson form factors, we note that the general angular condition for the spin‐1 systems is satisfied only if the zero‐mode contribution in the helicity zero‐to‐zero amplitude is properly taken into account. Discussions follow on the scaling law and the subleading power corrections for these form factor analyses.