Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A possible anthropic solution to the Strong CP problem   We point out that the long-standing strong CP problem may be resolved by an
anthropic argument. The key ideas are: (i) to allow explicit breaking(s) of the
Peccei-Quinn symmetry which reduces the strong CP problem to the cosmological
constant problem, and (ii) to conjecture that the probability distribution of
the vacuum energy has a mild pressure towards higher values. The cosmological
problems of the (s)axion with a large Peccei-Quinn scale are absent in our
mechanism, since the axion acquires a large mass from the explicit breaking.

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The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
36
The categories of this paper are: cmp-lg
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio