Measuring transverse spin correlations by 4-particle correlations in $e^+ e^-\to 2 \ {\rm jets}$

TL;DR

This work proposes a method to measure the transverse-spin fragmentation function by exploiting azimuthal correlations between four hadrons produced in e+e- → 2 jets. It provides a LO theoretical framework linking the observable to a nonperturbative analyzing power and outlines a detailed experimental protocol to extract the signal, including flavor and momentum-based selection to maximize sensitivity. The authors discuss systematic effects, Monte-Carlo cross-checks, and the statistical requirements, offering guidance on feasible measurements at contemporary e+e- colliders. If successful, this approach would enable quark polarimetry through jet fragmentation, filling a gap in twist-2 spin measurements and informing future spin-physics programs.

Abstract

The azimuthal distribution of pairs of particles in a jet is sensitive to the transverse polarization of the quark initiating the jet, but with a sensitivity that involves a nonperturbative analyzing power. We show in detail how to measure the analyzing power from 4-hadron correlations in $e^+ e^- \to 2 \ {\rm jets}$. We explain the combinations of particle flavor that are likely to give the biggest effect.

Figures (2)

• Figure 1: Schematic representation of fragmentation of jets.
• Figure 2: Quark diagrams for production of $K^{+}K^{-}\,\pi ^{-}\bar{K}^{0}$. The left-hand diagram corresponds to the lower right sub-box of box $\{4,9\}$) in table \ref{['table:CC1']}, and the right-hand diagram corresponds to the upper right sub-box. The later ($\circ$) is less favored than the former ($\bullet$), due to the necessity of creating two $s\,\bar{s}$ pairs instead of one in the fragmentation process.