Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Testing the universality of the Collins function in pion-jet production
  at RHIC   By adopting a generalised parton model approach at leading order in QCD,
including spin and intrinsic parton motion effects, we study the Collins
azimuthal asymmetries for pions within a large-$p_T$ jet produced at
mid-rapidity in polarised hadronic collisions. Using available information on
the quark transversity distributions and the pion Collins functions, as
extracted from semi-inclusive deeply inelastic scattering and $e^+e^-\to h_1
h_2\, X$ processes, we compute estimates for the Collins asymmetries in
kinematical configurations presently investigated at RHIC by the STAR
Collaboration. Collins-like asymmetries, involving linearly polarised gluons,
are also considered. Our predictions, compared against available preliminary
data, show a very good agreement, even if some discrepancies, to be further
scrutinized both theoretically and experimentally, appear in the transverse
momentum dependence of the Collins asymmetry. These results are in favour of
the predicted universality of the Collins function and of a mild, if any,
evolution with the hard scale of the asymmetries.

11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
19
The categories of this paper are: eess
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat