Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comment on the "Second dip as a signature of ultrahigh energy proton
  interactions with cosmic microwave background radiation" by V.Berezinsky,
  A.Gazizov and K.Kachelriess   A new feature in the spectrum of ultra high energy cosmic rays (UHECR) has
been announced in the paper by Berezinsky, Gazizov and Kachelriess. The ratio
of the solution of the exact transport equation to its solution in the
continuous energy loss limit shows intriguing features which, according to the
Authors, are related to the very nature of the energy loss processes of
UHECR:the very sharp second dip predicted at 6.3x10^19 eV can be used as an
energy calibration point and also as the UHECR mass indicator for big future
cosmic ray experiments. In the present paper we would like to advocate that
this statement is an overinterpretation. The second dip is a result of an
inapproriate approximation used, and thus it can't help to understand the
nature of UHECR in any way.

24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
16
The categories of this paper are: stat
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex