https://doi.org/10.1140/epjc/s10052-019-7551-4
Regular Article - Theoretical Physics
Single-spin asymmetries in 
within a TMD approach: role of the color octet mechanism
1
Dipartimento di Fisica, Università di Cagliari, Cittadella Universitaria, 09042, Monserrato, CA, Italy
2
INFN, Sezione di Cagliari, Cittadella Universitaria, 09042, Monserrato, CA, Italy
* e-mail: umberto.dalesio@ca.infn.it
Received:
25
October
2019
Accepted:
6
December
2019
Published online:
24
December
2019
We calculate the transverse single-spin asymmetry (SSA) for 
production in proton-proton collisions, within non-relativistic QCD, employing the transverse momentum dependent, generalized parton model, which includes both spin and intrinsic motion effects. In particular, we study the role of the color octet mechanism in accessing the gluon Sivers function. In doing that, we also show, within this approach, how the singularities coming from color octet terms in the low-
region can be handled, leading to finite cross sections. Predictions for both unpolarized cross sections and SSAs are given and compared against PHENIX data. Estimates for LHCb in the fixed target mode are also presented.
© The Author(s), 2019
