Deforming the theory lambda-phi-4 along the parameters and fields   gradient flows
  Considering the action for the theory $\lambda\phi^{4}$ for a massive scalar bosonic field as an entropy functional on the space of coupling constants and on the space of fields, we determine the gradient flows for the scalar field, the mass, and the self-interaction parameter. When the flow parameter is identified with the energy scale, we show that there exist phase transitions between unbroken exact symmetry scenarios and spontaneous symmetry breaking scenarios at increasingly high energies. Since a non-linear heat equation drives the scalar field through a {\it reaction-diffusion} process, in general the flows are not reversible, mimicking the renormalization group flows of the $c$-theorem; the deformation of the field at increasingly high energies can be described as non-linear traveling waves, or solitons associated to self-similar solutions 
R. Cartas-Fuentevilla, A. Olvera-Santamaria
hep-th math-ph math.MP