Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Small scale problems of the $\Lambda$CDM model: a short review   The $\Lambda$CDM model, or concordance cosmology, as it is often called, is a
paradigm at its maturity. It is clearly able to describe the universe at large
scale, even if some issues remain open, such as the cosmological constant
problem , the small-scale problems in galaxy formation, or the unexplained
anomalies in the CMB. $\Lambda$CDM clearly shows difficulty at small scales,
which could be related to our scant understanding, from the nature of dark
matter to that of gravity; or to the role of baryon physics, which is not well
understood and implemented in simulation codes or in semi-analytic models. At
this stage, it is of fundamental importance to understand whether the problems
encountered by the $\Lambda$DCM model are a sign of its limits or a sign of our
failures in getting the finer details right. In the present paper, we will
review the small-scale problems of the $\Lambda$CDM model, and we will discuss
the proposed solutions and to what extent they are able to give us a theory
accurately describing the phenomena in the complete range of scale of the
observed universe.

24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
21
The categories of this paper are: adap-org
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an