Abstract
We apply recent developments in large momentum effective theory (LaMET) to formulate a non-perturbative calculation of the single-transverse spin asymmetry in terms of the quasi transverse-momentum-dependent quark distribution functions from the so-called Sivers mechanism. When the spin asymmetry is defined as the ratio of the quark Sivers function over the spin averaged distribution, it can be directly calculated in terms of the relevant quasi distributions with the soft functions and perturbative matching kernels cancelling out. Apart from the general formula presented, we have verified the result in the small transverse distance limit at one-loop order, which reduces to a collinear expansion at twist-three level.
Highlights
Transverse-momentum-dependent (TMD) parton distribution functions (PDFs, TMDPDFs) are one of the important ingredients in nucleon tomography and a central focus of hadron physics research in recent years and especially at the future Electron-Ion Collider [1,2]
large momentum effective theory (LaMET) is based on the observation that parton physics defined in terms of lightcone correlations can be obtained from time-independent Euclidean correlations through a well-defined effective field theory (EFT) expansion as well as matching and running
We study single transverse-spin asymmetries in the region where the transverse momentum is on the order of ΛQCD, focusing on the nonperturbative calculation of the relevant TMDPDF—the quark Sivers function [28]—in terms of a Euclidean-space quasidistribution
Summary
Transverse-momentum-dependent (TMD) parton distribution functions (PDFs, TMDPDFs) are one of the important ingredients in nucleon tomography and a central focus of hadron physics research in recent years and especially at the future Electron-Ion Collider [1,2]. A generic argument to demonstrate the matching between the quasi-Sivers function and the light-cone Sivers function will be presented based on the factorization of the hard, collinear and soft gluon radiation contributions for the TMDPDFs. Because the matching coefficient only concerns hard gluon radiation, it does not depend on the spin structure of the nucleon. Our calculations are based on collinear twist-three quark-gluon-quark correlation functions, and we compute the quasi-Sivers function in terms of the QiuSterman matrix element [33,34,35,36,37] (defined below) This can be compared to the light-cone quark Sivers function calculated in the same framework [38,39,40,41,42,43,44] and the associated matching coefficient can be obtained.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
