Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Same Period Emission and Recombination in Non-Sequential Double
  Recombination High-Harmonic Generation in H$_2$   Non-sequential double recombination (NSDR) high-order harmonic generation
(HHG) is studied in a molecular system. We observe a unique molecular
two-electron effect with a characteristic cutoff in the HHG spectrum at higher
energies than what was previously seen for NSDR HHG in atoms. The effect is
corroborated with a classical model where it is found that the effect is
sensitive to the molecular potential and originates from same period emission
and recombination (SPEaR) of two electrons. The effect persists for
intermediate nuclear distances of $R \gtrsim 8.0$ a.u.

17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess