Transverse Polarization of Hyperons Produced in Semi-Inclusive Deep Inelastic Scattering

Abstract

We study the transverse polarization of hyperons produced in semi-inclusive deep inelastic scattering, ep → eΛ ↑ X, in the framework of the collinear twist-3 factorization. The cross section from the twist-3 distribution functions and the twist-3 quark fragmentation functions is computed in the leading order with respect to the QCD coupling constant. The constraint relations among the twist-3 FFs are taken into account to simplify the formula. The formula is relevant to large-P T hyperon production in the future Electron-Ion-Collider experiment.

Twist-3 Gluon Fragmentation Contribution to Hyperon Polarization in Semi-Inclusive Deep Inelastic Scattering

“…is a space-like momentum satisfying q t • p = q t • P h = 0. As in [1], we work in the hadron frame [10] (See…”

“…In a recent paper [1], three of the present authors studied the transverse polarization of hyperons produced in semi-inclusive deep inelastic scattering, ep → eΛ ↑ X. For a large-P T hyperon production, this process can be analyzed in the framework of the collinear factorization, in which the polarization appears as a twist-3 observable in the absence of a leading twist-2 effect.…”

“…The twist-3 FFs in (ii) are chiral-even, and both (a) quark and (b) gluon types of twist-3 FFs contribute. In [1], the twist-3 polarized cross section for ep → eΛ ↑ X from the above (i) and (ii)(a) was derived in the leading order (LO) with respect to the QCD coupling constant. As a sequel to [1], we will derive in this paper the LO cross section from (ii)(b), which completes the LO twist-3 cross section for this process.…”

“…In [1], the twist-3 polarized cross section for ep → eΛ ↑ X from the above (i) and (ii)(a) was derived in the leading order (LO) with respect to the QCD coupling constant. As a sequel to [1], we will derive in this paper the LO cross section from (ii)(b), which completes the LO twist-3 cross section for this process. Since the gluons are ample in the collision environment and the twist-3 quark and gluon FFs mix under renormalization, the effect of (ii)(b) could be as important as (ii)(a).…”

“…Here we apply the method to ep → eΛ ↑ X. Since the kinematics for this process was described in [1] and the method is in parallel to the case for pp → Λ ↑ X [4], our presentation in this paper will be brief, referring to those papers for the details.…”