- Proca action
physics, in the area of field theory, the Proca action describes a massive spin-1 field of mass m in Minkowski spacetime. The field involved is a real vector fieldA. The Lagrangian densityis given by:
The above presumes the
metric signature(+---). Here, "c" is the speed of lightand is Dirac's constant. In the dimensionless unitscommonly employed in theoretical physics, these may both be taken to be one. The Euler-Lagrange equationof motion is (this is also called the Proca equation):
which is equivalent to the conjunction of
which is the
Lorenz gauge condition. The Proca equation is closely related to the Klein-Gordon equation.
The Proca action is the gauge-fixed version of the
Stückelberg actionvia the Higgs mechanism.
Quantizing the Proca action requires the use of
second class constraints.
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