Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Intrinsic parton motion soft mechanisms and the longitudinal spin
  asymmetry A_LL in high energy pp -> pi X   The longitudinal double spin asymmetry A_LL in the reaction pp --> pi X has
been measured at RHIC with extremely interesting consequences. If the gluon
polarization in a proton were as big as needed to resolve the famous "spin
crisis" then A_LL would be large and positive. Latest RHIC results indicate
that A_LL is small and disfavour large positive values of the gluon
polarization. We examine whether the soft mechanisms (Collins, Sivers,
Boer-Mulders), essential for generating transverse single spin asymmetries,
have any significant influence on A_LL, and whether they could alter the
conclusion that the gluon polarization is necessarily small. It turns out that
the contribution from these effects is essentially negligible.

11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
2
The categories of this paper are: math
6
The categories of this paper are: astro-ph
9
The categories of this paper are: nlin