Transverse single-spin asymmetries in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si27.svg"> <mml:mi>γ</mml:mi> </mml:math> SIDIS as a direct probe of quark-gluon-quark longitudinal momentum structure

Transverse single-spin asymmetries in the semi-inclusive deep-inelastic production of isolated photons (γSIDIS), AUTγSIDIS, provide an unprecedented opportunity to extract the quark-gluon-quark correlators FFT(x,x′) and GFT(x,x′) point-by-point in their full support x,x′. We utilize realistic models for these functions, based on input from the Sivers transverse momentum dependent parton distribution function and imposing constraints from the d2 matrix element calculated in lattice QCD, in order to provide numerical estimates for AUTγSIDIS at the Electron-Ion Collider (EIC). We thoroughly explore the EIC phase space in order to isolate in which regions the asymmetry can be sizable, finding it can be as much as 10% or larger for certain kinematics. Given that FFT(x,x′) and GFT(x,x′) are basically unknown, AUTγSIDIS will be an important future measurement to learn about multi-parton correlations in the nucleon.