Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New theoretical results in ultrarelativistic ultraperipheral lead-lead
  collisions   We study dilepton, proton-antiproton and diphoton production in
ultraperipheral lead-lead collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 and 5.5
TeV. The nuclear calculations are based on equivalent photon approximation in
the impact parameter space. For correct description of the $\gamma\gamma \to
p\bar{p} $ Belle data we include the proton-exchange, the $f_2(1270)$ and
$f_2(1950)$ s-channel exchanges, as well as the handbag mechanism. For four
muon production, we take into account electromagnetic (two-photon)
double-scattering production and direct $\gamma\gamma$ production of four muons
in one scattering. The cross sections for elementary $\gamma\gamma \to
\gamma\gamma$ subprocess are calculated including three different mechanisms:
box diagrams with leptons and quarks in the loops, a VDM-Regge contribution
with virtual intermediate hadronic excitations of the photons and the two-gluon
exchange contribution. We find that the cross section for elastic
$\gamma\gamma$ scattering could be measured in the lead-lead collisions for the
diphoton invariant mass up to $W_{\gamma\gamma} \approx$ 15 - 20 GeV. Our
Standard Model predictions are compared with a recent ATLAS experimental
result.
  We discuss results for PbPb$\to$PbPb$\mu^+\mu^-\mu^+\mu^-$,
PbPb$\to$PbPb$e^+e^-e^+e^-$, PbPb$\to$PbPb$p\bar{p}$ and
PbPb$\to$PbPb$\gamma\gamma$ reactions at LHC energy.

11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio