Single-spin asymmetries at two loops

Abstract

We find a novel mechanism for generating transverse single-spin asymmetry (SSA) in semi-inclusive deep inelastic scattering, distinct from the known ones which involve the Sivers and Collins functions, or their collinear twist-three counterparts. It is demonstrated that a phase needed for SSA can be produced purely within a parton-level cross section starting at two loops. We identify the complete set of two-loop diagrams for SSA, and discuss their gauge invariance and collinear factorization which features the $g_T$ distribution function. In the $k_T$ factorization framework, many more sources for SSA exist, and contributions from all possible two-parton transverse-momentum-dependent parton distribution functions are presented up to two loops and twist three.

21 pages, 14 figures

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Cited by in corpus (13)

• Updated QCD global analysis of single transverse-spin asymmetries I: Extracting $\tilde{H}$, and the role of the Soffer bound and lattice QCD
• Exact Relations for Twist-3 Gluon Distribution and Fragmentation Functions from Operator Identities
• Neutrino-tagged jets at the Electron-Ion Collider
• The $g_T(x)$ contribution to single spin asymmetries in SIDIS
• Transverse Polarization of Hyperons Produced in Semi-Inclusive Deep Inelastic Scattering
• Perturbative $T$-odd asymmetries in the Drell-Yan process revisited
• NLO corrections and factorization for transverse single-spin asymmetries
• On the odderon mechanism for transverse single spin asymmetry in the Wandzura-Wilczek approximation
• Transverse Nucleon Single-Spin Asymmetry for Single-Inclusive Hadron and Jet Production at NLO Accuracy
• Gluonic contributions to semi-inclusive DIS in the target fragmentation region
• T-odd proton-helicity asymmetry in semi-inclusive DIS in perturbative QCD
• Single spin asymmetry in forward $pA$ collisions from Pomeron-Odderon interference
• Transverse-single-spin asymmetries of charged pions at midrapidity in transversely polarized $p+p$ collisions at $\sqrt{s}=200$ GeV