Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Vacuum statistics and stability in axionic landscapes   We investigate vacuum statistics and stability in random axionic landscapes.
For this purpose we developed an algorithm for a quick evaluation of the
tunneling action, which in most cases is accurate within 10%. We find that
stability of a vacuum is strongly correlated with its energy density, with
lifetime rapidly growing as the energy density is decreased. The probability
$P(B)$ for a vacuum to have a tunneling action $B$ greater than a given value
declines as a slow power law in $B$. This is in sharp contrast with the studies
of random quartic potentials, which found a fast exponential decline of $P(B)$.
Our results suggest that the total number of relatively stable vacua (say, with
$B> 100$) grows exponentially with the number of fields $N$ and can get
extremely large for $N\gtrsim 100$. The problem with this kind of model is that
the stable vacua are concentrated near the absolute minimum of the potential,
so the observed value of the cosmological constant cannot be explained without
fine-tuning. To address this difficulty, we consider a modification of the
model, where the axions acquire a quadratic mass term, due to their mixing with
4-form fields. This results in a larger landscape with a much broader
distribution of vacuum energies. The number of relatively stable vacua in such
models can still be extremely large.

27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an