. In curved spacetime, the Dirac equation for a spin-1/2 fermion with an electromagnetic field [A.sub.[mu]] takes on the form
In fact, besides the usual ambiguity in the choice of the quantum representation for a fixed classical field description, time-dependent scalings of the fermion field
modes (after an appropriate mode decomposition) were also allowed, effectively modifying the original D'Eath and Halliwell parametrization of the system.
A modified form of local gauge invariance in which fermion field
phase is allowed to vary with each space point but not each time point, leads to the introduction of a new compensatory field different from the electromagnetic field associated with the photon.
Passos, "Aharonov-Bohm effect for a fermion field
in a planar black hole "spacetime"," The European Physical Journal C, vol.
In Section 3 we investigate localization of the zero mode of the fermion field
on the brane which is derived from a polynomial potential.
As the angular momentum J = -i[[partial derivative].sub.[phi]] + (s/2)[[sigma].sup.z] commutes with the H, it is possible to decompose the fermion field
where g is the positive coupling constant and the fermion field
[psi](x) has scale dimension 1/2 .
As it is well known, Green's functions in the functional-integral approach are defined by means of the so-called generating functional with sources for the boson and fermion fields
, but the corresponding functional integrals cannot be evaluated exactly because the interaction part of the Hubbard Hamiltonian is quartic in the Grassmann fermion fields
which specifies the propagators of electromagnetic, Z-, [W.sup.[+ or -]]-boson, Higgs, and fermion fields
, and the interactions between these fields.
Matter fields (fermion fields
) are defined in the context of Mobius structures to be sections of vector bundles associated with Q.
The structure of the paper is the following: in Section 2, we introduce the Bogoliubov transformations in quantum field theory (QFT) and we study the energy-momentum tensor density for vacuum condensates of boson and fermion fields
. In Sections 3 and 4, we present the contribution given to the energy of the universe by thermal states, with reference to the Hawking and Unruh effects, by fields in curved space and by particle mixing phenomena.