Probing the three-gluon correlation functions by the single spin asymmetry inp↑p→DX

Abstract

We study the single transverse-spin asymmetry for the inclusive open-charm production in the pp-collision, p ↑ p → DX, induced by the three-gluon correlation functions in the polarized nucleon. We derive the corresponding twist-3 cross section formula in the leading order with respect to the QCD coupling constant. As in the case of the semi-inclusive deep inelastic scattering, ep ↑ → eDX, our result differs from the previous result in the literature. We also derive a "master formula" which expresses the twist-3 cross section in terms of the gg → cc hard scattering cross section. We present a model calculation of the asymmetry at the RHIC energy, demonstrating the sensitivity of the asymmetry on the form of the three-gluon correlation functions.

Transverse single spin asymmetries at smallxand the anomalous magnetic moment

“…A relation between k ⊥ momentum of the odderon and the collinear twist-3 C-odd tri-gluon correlation has been established. It is straightforward to extend our formalism to study SSAs in open charm production in pp collisions and in Drell-Yan/direct photon processes, which already have been calculated in the collinear twist-3 framework [40,41] (for earlier work, see [39]). It is our plan to further explore the possible difference/relation between the CGC formalism and the collinear twist-3 approach in computing SSAs at small x.…”

Operator constraints for twist-3 functions and Lorentz invariance properties of twist-3 observables

“…Much theoretical work has been performed over the years to develop the collinear twist-3 formalism needed to describe these proton-proton SSAs [14][15][16][17][19][20][21][22][23][24][25][26][27][28][29][30][31] and DSAs [32][33][34][35][36][37][38], including recent extensions to include fragmentation effects [26,27,29,30,38] and tri-gluon correlations [31,37,[39][40][41][42]. Nevertheless, whether this framework can provide a * tuf29138@temple.edu † koike@phys.sc.niigata-u.ac.jp ‡ metza@temple.edu § dpitonyak@quark.phy.bnl.gov ¶ marc.schlegel@uni-tuebingen.de definitive explanation of these observables (especially SSAs) remains an open question.…”

A New Mechanism for Generating a Single Transverse Spin Asymmetry

“…Hence our STSA-generating mechanism is distinctively different from the Collins [27] and Sivers [15,16] effects, and is more akin to (though still different from) the higher-twist mechanisms of [17][18][19][20][21][22][23][24][25][26].…”

“…(32a) stems from the multiple interactions with the target (higher-twist effects), and its contribution is in fact zero in the linearized (leading-twist) approximation. In this sense the above mechanism for generating STSA is similar in spirit to the higher-twist mechanisms of [17][18][19][20][21][22][23][24][25][26], though a detailed comparison of the diagrams appears to indicate that the two approaches are, in fact, different.…”

“…Being a part of the PDF, this is an intrinsically non-perturbative process. The asymmetry could also be generated in the partonic scattering processes themselves; since the leading-order scattering process does not generate an asymmetry, any contribution would come from "higher-twist" terms in the interaction, as suggested in [17][18][19][20][21][22][23][24][25][26]. Such an asymmetry generated by the interaction may be perturbative, depending on the kinematics.…”