Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational "seesaw" and light bending in higher-derivative gravity   Local gravitational theories with more than four derivatives have remarkable
quantum properties, e.g., they are super-renormalizable and may be unitary in
the Lee-Wick sense. Therefore, it is important to explore also the IR limit of
these theories and identify observable signatures of the higher derivatives. In
the present work we study the scattering of a photon by a classical external
gravitational field in the sixth-derivative model whose propagator contains
only real, simple poles. Also, we discuss the possibility of a gravitational
seesaw-like mechanism, which could allow the make up of a relatively small
physical mass from the huge massive parameters of the action. If possible, this
mechanism would be a way out of the Planck suppression, affecting the
gravitational deflection of low energy photons. It turns out that the mechanism
which actually occurs works only to shift heavier masses to the further UV
region. This fact may be favourable for protecting the theory from
instabilities, but makes experimental detection of higher derivatives more
difficult.

20
The categories of this paper are: acc-phys
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con