Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comparison of different approaches to the longitudinal momentum spread
  after tunnel ionization   We introduce a method to investigate the longitudinal momentum spread
resulting from strong-field tunnel ionization of Helium which, unlike other
methods, is valid for all ellipticities of laser pulse. Semiclassical models
consisting of tunnel ionization followed by classical propagation in the
combined ion and laser field reproduce the experimental results if an initial
longitudinal spread at the tunnel exit is included. The values for this spread
are found to be of the order of twice the transverse momentum spread.

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The categories of this paper are: hep-ph
16
The categories of this paper are: stat
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con