Colour unwound - disentangling colours for azimuthal asymmetries in Drell-Yan scattering

Boer, Daniël; van Daal, Tom; Gaunt, Jonathan; Kasemets, Tomas; Mulders, Piet; Gaunt, Jonathan

doi:10.21468/SciPostPhys.3.6.040

SciPost Physics

Colour unwound - disentangling colours for azimuthal asymmetries in Drell-Yan scattering

Daniël Boer, Tom van Daal, Jonathan R. Gaunt, Tomas Kasemets, Piet J. Mulders

SciPost Phys. 3, 040 (2017) · published 19 December 2017

doi: 10.21468/SciPostPhys.3.6.040
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Abstract

It has been suggested that a colour-entanglement effect exists in the Drell-Yan cross section for the 'double T-odd' contributions at low transverse momentum $Q_T$, rendering the colour structure different from that predicted by the usual factorisation formula [1]. These T-odd contributions can come from the Boer-Mulders or Sivers transverse momentum dependent distribution functions. The different colour structure should be visible already at the lowest possible order that gives a contribution to the double Boer-Mulders (dBM) or double Sivers (dS) effect, that is at the level of two gluon exchanges. To discriminate between the different predictions, we compute the leading-power contribution to the low-$Q_T$ dBM cross section at the two-gluon exchange order in the context of a spectator model. The computation is performed using a method of regions analysis with Collins subtraction terms implemented. The results conform with the predictions of the factorisation formula. In the cancellation of the colour entanglement, diagrams containing the three-gluon vertex are essential. Furthermore, the Glauber region turns out to play an important role - in fact, it is possible to assign the full contribution to the dBM cross section at the given order to the region in which the two gluons have Glauber scaling. A similar disentanglement of colour is found for the dS effect.

TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.3.6.040
TI  - Colour unwound - disentangling colours for azimuthal asymmetries in Drell-Yan scattering
PY  - 2017/12/19
UR  - https://scipost.org/SciPostPhys.3.6.040
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 3
IS  - 6
SP  - 040
A1  - Boer, Daniël
AU  - van Daal, Tom
AU  - Gaunt, Jonathan
AU  - Kasemets, Tomas
AU  - Mulders, Piet
AU  - Gaunt, Jonathan
AB  - It has been suggested that a colour-entanglement effect exists in the Drell-Yan cross section for the 'double T-odd' contributions at low transverse momentum $Q_T$, rendering the colour structure different from that predicted by the usual factorisation formula [1]. These T-odd contributions can come from the Boer-Mulders or Sivers transverse momentum dependent distribution functions. The different colour structure should be visible already at the lowest possible order that gives a contribution to the double Boer-Mulders (dBM) or double Sivers (dS) effect, that is at the level of two gluon exchanges. To discriminate between the different predictions, we compute the leading-power contribution to the low-$Q_T$ dBM cross section at the two-gluon exchange order in the context of a spectator model. The computation is performed using a method of regions analysis with Collins subtraction terms implemented. The results conform with the predictions of the factorisation formula. In the cancellation of the colour entanglement, diagrams containing the three-gluon vertex are essential. Furthermore, the Glauber region turns out to play an important role - in fact, it is possible to assign the full contribution to the dBM cross section at the given order to the region in which the two gluons have Glauber scaling. A similar disentanglement of colour is found for the dS effect.
ER  -

@Article{10.21468/SciPostPhys.3.6.040,
	title={{Colour unwound - disentangling colours for azimuthal asymmetries in Drell-Yan scattering}},
	author={Daniël Boer and Tom van Daal and Jonathan R. Gaunt and Tomas Kasemets and Piet J. Mulders},
	journal={SciPost Phys.},
	volume={3},
	pages={040},
	year={2017},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.3.6.040},
	url={https://scipost.org/10.21468/SciPostPhys.3.6.040},
}

Cited by 4

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Drell-Yan scattering Gluons

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¹ Daniël Boer,
² ³ Tom van Daal,
² ³ Jonathan Gaunt,
² ³ Tomas Kasemets,
² ³ Piet Mulders,
Jonathan Gaunt

Funder for the research work leading to this publication

European Research Council [ERC]