Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comprehensive Solution to the Cosmological Constant, Zero-Point Energy,
  and Quantum Gravity Problems   We present a solution to the cosmological constant, the zero-point energy,
and the quantum gravity problems within a single comprehensive framework. We
show that in quantum theories of gravity in which the zero-point energy density
of the gravitational field is well-defined, the cosmological constant and
zero-point energy problems solve each other by mutual cancellation between the
cosmological constant and the matter and gravitational field zero-point energy
densities. Because of this cancellation, regulation of the matter field
zero-point energy density is not needed, and thus does not cause any trace
anomaly to arise. We exhibit our results in two theories of gravity that are
well-defined quantum-mechanically. Both of these theories are locally conformal
invariant, quantum Einstein gravity in two dimensions and Weyl-tensor-based
quantum conformal gravity in four dimensions (a fourth-order derivative quantum
theory of the type that Bender and Mannheim have recently shown to be
ghost-free and unitary). Central to our approach is the requirement that any
and all departures of the geometry from Minkowski are to be brought about by
quantum mechanics alone. Consequently, there have to be no fundamental
classical fields, and all mass scales have to be generated by dynamical
condensates. In such a situation the trace of the matter field energy-momentum
tensor is zero, a constraint that obliges its cosmological constant and
zero-point contributions to cancel each other identically, no matter how large
they might be. Quantization of the gravitational field is caused by its
coupling to quantized matter fields, with the gravitational field not needing
any independent quantization of its own. With there being no a priori classical
curvature, one does not have to make it compatible with quantization.

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The categories of this paper are: funct-an
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
0
The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom