Extension and Applications of a Variational Approach with Deformed Derivatives

We have recently presented an extension of the standard variational calculus to include the presence of deformed derivatives in the Lagrangian of a system of particles and in the Lagrangian density of field-theoretic models. Classical Euler-Lagrange equations and the Hamiltonian formalism have been re-assessed in this approach. Whenever applied to a number of physical systems, the resulting dynamical equations come out to be the correct ones found in the literature, specially with mass-dependent and with non-linear equations for classical and quantum-mechanical systems. In the present contribution, we extend the variational approach with the intervalar form of deformed derivatives to study higher-order dissipative systems, with application to concrete situations, such as an accelerated point charge - this is the problem of the Abraham-Lorentz-Dirac force - to stochastic dynamics like the Langevin, the advection-convection-reaction and Fokker-Planck equations, Korteweg-de Vries equation, Landau-Lifshits-Gilbert equation and the Caldirola-Kanai Hamiltonian. By considering these different applications, we show that the formulation investigated in this paper may be a simple and promising path for dealing with dissipative, non-linear and stochastic systems through the variational approach.