Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Threshold for Laser-Driven Linear Particle Acceleration in Unbounded
  Vacuum   We hypothesize that a charged particle in unbounded vacuum can be
substantially accelerated by a force linear in the electric field of a
propagating electromagnetic wave only if the accelerating field is capable of
bringing the particle to a relativistic energy in its initial rest frame during
the interaction. We consequently derive a general formula for the acceleration
threshold of such schemes and support our conclusion with the results of
numerical simulations over a broad range of parameters for different kinds of
pulsed laser beams.

11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
9
The categories of this paper are: nlin