Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of 4d Gauge Theory and Gravity from their 3d
  versions--Asymptotic Disappearance of Space and Time (ADST) Scenario--   An exotic scenario of our universe is proposed in which our universe starts
from zero space-time dimensions (0d), namely, a set of discrete points, it
increases the (continuous) dimensionality during the cooling down of it, and
finally arrives at the present four space-time dimensions (4d). This scenario
may be called asymptotic disappearance (or discretization) of space-time (ADST)
scenario. The final stage of the scenario is to generate dynamically 4d from
the 3d, which is shown to be possible for both gauge theory and gravity,
including the standard model. To examine the validity of the scenario, 4d QED
generated from its 3d version at high energy is studied, in which one spatial
dimension is discretized with a lattice constant $a$. From the LEP2 experiment
on $e^+ e^- \to \gamma \gamma$, $a$ is constrained to satisfy $a \le 461$ GeV.
Expected bound on $a$ at future $e^+ e^-$ linear collider is discussed. The
finite size of $a$ modifies the dispersion relation, causing the violation of
Lorentz symmetry. Then, the paradox of observing 20 TeV $\gamma$ rays from the
active galaxy Markarian 501 may disappear, overcoming the GZK cut.

20
The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex