Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dominance of $\gamma$-$\gamma$ electron-positron pair creation in a
  plasma driven by high-intensity lasers   Creation of electrons and positrons from light alone is a basic prediction of
quantum electrodynamics, but yet to be observed. Here we show that it is
possible to create ${>}10^8$ positrons by dual laser irradiation of a
structured plasma target, at intensities of $2 \times 10^{22}
\mathrm{W}\mathrm{cm}^{-2}$. In contrast to previous work, the pair creation is
primarily driven by the linear Breit-Wheeler process ($\gamma\gamma \to e^+
e^-$), not the nonlinear process assumed to be dominant at high intensity,
because of the high density of $\gamma$ rays emitted inside the target. The
favorable scaling with laser intensity of the linear process prompts
reconsideration of its neglect in simulation studies, but also permits positron
jet formation at intensities that are already experimentally feasible.
Simulations show that the positrons, confined by a quasistatic plasma magnetic
field, may be accelerated by the lasers to energies $> 200$ MeV.

18
The categories of this paper are: econ
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an