Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Causality Constraints in Large $N$ QCD Coupled to Gravity   Confining gauge theories contain glueballs and mesons with arbitrary spin,
and these particles become metastable at large $N$. However, metastable higher
spin particles, when coupled to gravity, are in conflict with causality. This
tension can be avoided only if the gravitational interaction is accompanied by
interactions involving other higher spin states well below the Planck scale
$M_{\rm pl}$. These higher spin states can come from either the QCD sector or
the gravity sector, but both these resolutions have some surprising
implications. For example, QCD states can resolve the problem since there is a
non-trivial mixing between the QCD sector and the gravity sector, requiring all
particles to interact with glueballs at tree-level. If gravity sector states
restore causality, any weakly coupled UV completion of the gravity-sector must
have many stringy features, with an upper bound on the string scale. Under the
assumption that gravity is weakly coupled, both scenarios imply that the theory
has a stringy description above $N\gtrsim \frac{M_{\rm pl}}{\Lambda_{\rm
QCD}}$, where $\Lambda_{\rm QCD}$ is the confinement scale.

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The categories of this paper are: chem-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph