Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Origin of the tail in Green's functions in odd dimensional space-times   It is well known that the scalar field Green's function in odd dimensions has
a tail, i.e. a non-zero support inside the light cone, which in turn implies
that the Huygens' principle is violated. However, the reason behind this
behavior is still not quite clear. In this paper we shed more light on the
physical origin of the tail by regularizing the term which is usually ignored
in the literature since it vanishes due to the action of the delta function.
With this extra term the Green's function does not satisfy the source-free wave
equation (in the region outside of the source). We show that this term
corresponds to a charge imprinted on the light cone shell. Unlike the vector
field charge, a moving scalar field charge is not Lorentz invariant and is
contracted by the relativistic $\sqrt{1-v^2}$ factor. If a scalar charge is
moving at the speed of light, it appears to be zero in the static (with respect
to the original physical charge) observer's frame. However, the field it
sources is not entirely on the light cone. Thus, it is likely that this hidden
charge sources the mysterious tail in odd dimensions.

27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
6
The categories of this paper are: astro-ph
11
The categories of this paper are: hep-lat