Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On mass hierarchies in orientifold vacua   We analyze the problem of the hierarchy of masses and mixings in orientifold
realizations of the Standard Model. We find bottom-up brane configurations that
can generate such hierarchies.

32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin