Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravity effects of the quantum vacuum. Dark energy and dark matter   The stress-energy tensor of the quantum vacuum is studied for the particular
case of quantum electrodynamics (QED), that is a fictituous universe where only
the electromagnetic and the electron-positron fields exist. The integrals
involved are ultraviolet divergent but it is suggested that a natural cut-off
may exist. It is shown that, in spite of the fact that the stress-energy tensor
of the electromagnetic field alone is traceless (i.e the pressure P equals 1/3
the energy density u), the total QED tensor is proportional to the metric
tensor to a good approximation (i. e. P = -u). It is proposed that there is a
cosmological constant in Einstein equation that exactly balances the
stress-energy of the vacuum. It is shown that vacuum fluctuations give rise to
a modified spacetime metric able to explain dark energy. Particular excitations
of the vacuum are studied that might explain dark matter.

21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph