Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Particle Acceleration by Static Black Holes in a Model of $f(R)$ Gravity   Particle collisions are considered within the context of $f(R)$ gravity
described by $f(R)=R+2\alpha\sqrt{R}$, where $R$ stands for the Ricci scalar
and $\alpha$ is a non-zero constant. The center of mass (CM) energy of head-on
colliding particles moving in opposite radial directions near the naked
singularity/horizon are considered. Collision of particles in the same
direction near the event horizon yields finite energy while the energy of
oppositely moving particles grows unbounded. Addition of a cosmological
constant does not change the feature. Collision of a massless outgoing photon
with an infalling particle and collision of two oppositely moving photons
following null-geodesics are also taken into account.

32
The categories of this paper are: atom-ph
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
6
The categories of this paper are: astro-ph
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat