1201.5890 (Yuri V. Kovchegov et al.)

A New Mechanism for Generating a Single Transverse Spin Asymmetry    [PDF]

Yuri V. Kovchegov, Matthew D. Sievert

We propose a new mechanism for generating a single transverse spin asymmetry
(STSA) in polarized proton--proton and proton-nucleus collisions in the
high-energy scattering approximation. In this framework the STSA originates
from the q -> q G splitting in the projectile (proton) light-cone wave function
followed by a perturbative (C-odd) odderon interaction, together with a C-even
interaction, between the projectile and the target. We show that the obtained
expression for the STSA of the produced quarks is in qualitative agreement with
experiment: STSA decreases with decreasing projectile x_F and is a
non-monotonic function of the transverse momentum k_T, peaking near the
saturation scale Q_s in our framework. Our mechanism predicts that the quark
STSA in proton-nucleus collisions should be much smaller than in proton-proton
collisions. We also observe that in our formalism the STSA for prompt photons
is zero.

View original: http://arxiv.org/abs/1201.5890