Lagrange density for massless scalar field
63807
Scalar Field Theories
44342
Negative Mass and gravitation
983
Use partial or covariant derivatives when deriving equations of a field theory?
126390
Covariance of Euler-Lagrange equations under change of generalized coordinates
94173
Deriving the Lagrangian for a free particle
99312
Why Lagrangian is negative number for a relativistic massive point particle?
94004
Boundedness of general relativity Hamiltonian
35409
Massless charged particles
63402
Euler-Lagrange equation in curved spacetime: how to calculate $\partial \mathcal{L}/\partial(\nabla_\nu A_\mu)$?
48930
Least-action classical electrodynamics without potentials
141447
Inverse Square Law and extra space dimensions
4989
Why are there only derivatives to the first order in the Lagrangian?
87914
Contradictory result for scalar-field propagator from Feynman rules and LSZ formula
13644
Is the change in the Lagrangian always a total derivative for symmetry transformations of the action?
112073
What does a Lagrangian of the form $L=m^2\dot x^4 +U(x)\dot x^2 -W(x)$ represent?
60787
Natural density of solvable quintics
116513
Distributional Laplacian of logarithm and the Dirac delta distribution