Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Laser-induced nonsequential double ionization: kinematic constraints for
  the recollision-excitation-tunneling mechanism   We investigate the physical processes in which an electron, upon return to
its parent ion, promotes a second electron to an excited state, from which it
subsequently tunnels. Employing the strong-field approximation and saddle-point
methods, we perform a detailed analysis of the dynamics of the two electrons,
in terms of quantum orbits, and delimit constraints for their momentum
components parallel to the laser-field polarization. The kinetic energy of the
first electron, upon return, exhibits a cutoff slightly lower than $10U_p$,
where $U_p$ is the ponderomotive energy, as in rescattered above-threshold
ionization (ATI). The second electron leaves the excited state in a direct
ATI-like process, with the maximal energy of $2U_p$. We also compute
electron-momentum distributions, whose maxima agree with our estimates and with
other methods.

4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess