Single spin asymmetries from a single Wilson loop

Daniël Boer, Piet Mulders, Jian Zhou, Miguel Echevarria

Research output: Contribution to JournalArticleAcademicpeer-review


We study the leading-power gluon transverse-momentum-dependent distributions (TMDs) of relevance to the study of asymmetries in the scattering off transversely polarized hadrons. Next-to-leading-order perturbative calculations of these TMDs show that at large transverse momentum they have common dynamical origins but that in the limit of a small longitudinal momentum fraction x, only one origin remains. We find that in this limit, only the dipole-type gluon TMDs survive and become identical to each other. At small x, they are all given by the expectation value of a single Wilson loop inside the transversely polarized hadron, the so-called spin-dependent odderon. This universal origin of transverse spin asymmetries at small x is of importance to current and future experimental studies, paving the way to a better understanding of the role of gluons in the three-dimensional structure of spin-polarized protons.
Original languageEnglish
Article number122001
JournalPhysical Review Letters
Issue number12
Publication statusPublished - 21 Mar 2016

Bibliographical note

5 pages, 1 figure. Various changes to the text, additional references, conclusions unchanged, version accepted for publication in Physical Review Letters


  • hep-ph


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