出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The comparison of form factors calculated from a single-particle current in different relativistic
quantum mechanic approaches evidences tremendous discrepancies. The role of constraints coming
from space-time translations is considered here with this respect. It is known that invariance
under these translations implies the energy-momentum conservation relation that is usually assumed
to hold globally. Transformations of the current under these translations, which lead to
this result, also imply constraints that have been ignored so far in relativistic quantum mechanic
approaches. An implementation of these constraints is discussed in the case of a model with two
scalar constituents. It amounts to incorporate selected two-body currents to all orders in the interaction.
Discrepancies for form factors in different approaches can thus be removed, contributing
to restore the equivalence of different approaches. Results for the standard front-form approach
(q 0) are found to fulfill the constraints and are therefore unchanged. The relation with results
from a dispersion-relation approach is also made.
