A question about effective action in QFT?
They say that for constant fields the effective potential in the tree approximately is given simply by minus the nonderivative terms in the Lagrangian density.I do not understand why the derivative terms are ''kinematic energy'' so that the potential equalling minimum expectation energy must abandons the kinematic energy(so abandons derivative terms).Because for example in KleinGordon Lagrangian the second order derivative(of fourvector) is proportional with square of mass(?) not being kinematic energy.
