Il Nuovo Cimento A (1965-1970)

, Volume 109, Issue 3, pp 271–279

The helicity of the free electromagnetic field and its physical meaning


DOI: 10.1007/BF02731014

Cite this article as:
Afanasiev, G.N. & Stepanovsky, Y.P. Nuov Cim A (1996) 109: 271. doi:10.1007/BF02731014


The notion of helicity for the free electromagnetic field is analysed. The generalized helicity is introduced which is a conserved quantity coinciding with the difference of the right and left circularly polarized photons composing the electromagnetic field. It seems that it completes the list of the zilch-type invariants found by Lipkin and Ragusa. The gauge-invariant expression for the energy of the free gravitational field is obtained which strongly resembles the well-known bilinear expression for the total number of photons composing the electromagnetic field.


11.10 - Field theory


12.90 - Miscellaneous theoretical ideas and models

Copyright information

© Società Italiana di Fisica 1996

Authors and Affiliations

  1. 1.Bogoliubov Laboratory of Theoretical PhysicsJoint Institute for Nuclear ResearchDubna, Moscow DistrictRussia
  2. 2.The Institute of Physics and TechnologyKharkovUkraine