Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Field Theories in Spaces with Neutral Signatures   We point out that quantum field theories based on the concept of Clifford
space and Clifford algebra valued-fields involve both positive and negative
energies. This is a consequence of the indefinite signature (p,q) of the
Clifford space. When the signature is neutral, p=q, then vacuum energy vanishes
and there is no cosmological constant problem. A question of the stability of
such theories in the presence of interactions arises. We investigate a toy
model of the harmonic oscillator in the space $M_{1,1}$. We have found that in
the presence of certain interactions the amplitude of oscillations can remain
finite. In general this is not the case and the amplitude grows to infinity,
but only when the two frequencies are exactly the same. When they are even
slightly different, the amplitude remains finite and the system is stable. We
show how such oscillator comes from the Stueckelberg action in curved space,
and how it can be generalized to field theories.

24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an