A covariant nonlocal Lagrangian for the description of the scalar kaonic sector

Understand

Mesons are extended objects, hence their interaction can be described by utilizing form factors.

• At the Lagrangian level, one can use nonlocal interaction terms.
• Here we describe two possible nonlocal Lagrangians leading to a 3D form factor: the first one is simple but does not fulfill covariance (if one insists on a 3D cutoff), the second extension is more involved but guarantees covariance.
• Such form factors are useful when calculating mesonic loops.