Photon merging and splitting in electromagnetic field inhomogeneities

Photon-graviton mixing in an electromagnetic field

Einstein-Maxwell theory implies the mixing of photons with gravitons in an external electromagnetic field. This process and its possible observable consequences have been studied at tree level for many years. We use the worldline formalism for obtaining an exact integral representation for the one-loop corrections to this amplitude due to scalars and fermions. We study the structure of this amp...

Photon splitting γ → νν̃ in an external magnetic field

High - energy photon splitting in a strong Coulomb field

The helicity amplitudes of the high-energy photon splitting in the external Coulomb field are obtained exactly in the parameter Zα. The cases of screened and unscreened potentials are investigated. The consideration is based on the quasiclassical approach, valid for small angles between all photon momenta. New representation of the qua-siclassical electron Green function is exploited. General e...

Photon Splitting in a Very Strong Magnetic Field.

Photon splitting in a very strong magnetic field is analyzed for energy ω < 2m. The amplitude obtained on the base of operator-diagram technique is used. It is shown that in a magnetic field much higher than critical one the splitting amplitude is independent on the field. Our calculation is in a good agreement with previous results of Adler and in a strong contradiction with recent paper of Me...

Merging and Splitting Eigenspace Models

We present new deterministic methods that given two eigenspace models, each representing a set of n-dimensional observations will: (1) merge the models to yield a representation of the union of the sets; (2) split one model from another to represent the difference between the sets; as this is done, we accurately keep track of the mean. These methods are more efficient than computing new eigensp...