Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Poincare' covariant light-front spectral function and transverse
  momentum distribution   In valence approximation the fermion correlator is simply related to the
light-front spectral function. Then the leading twist time-reversal even
transverse momentum distributions can be explicitly obtained from the
light-front wave function of the system and the twist-three distributions are
linear combinations of the transverse distributions at leading twist.

24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
26
The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
2
The categories of this paper are: math