Accessing quark helicity in $e^+e^-$ and SIDIS via dihadron correlations

TL;DR

This paper explores novel methods to measure quark helicity via dihadron correlations in electron-positron annihilation and SIDIS, addressing previous null results and proposing new experimental approaches and theoretical calculations.

Contribution

It introduces new methods for accessing helicity-dependent dihadron fragmentation functions in SIDIS and electron-positron experiments, along with a Monte Carlo calculation within the extended quark-jet model.

Findings

Explanation of zero results at BELLE experiment.

Introduction of new methods for helicity-dependent DiFF measurement.

Monte Carlo calculations of Fourier moments in the extended quark-jet model.

Abstract

The correlation between the longitudinal polarization of a fragmenting quark and the transverse momenta of the produced hadrons was predicted over two decades ago. Nevertheless, experimental searches in the electron-positron annihilation process, both through the so-called jet handedness measurements by the {\tt SLD} Collaboration and more recently via the measurements of the azimuthal asymmetry containing the helicity-dependent dihadron fragmentation function (DiFF) by the $\textrm{BELLE}$ Collaboration, did not yield a signal. We will first discuss our recent explanation of the zero result at $\textrm{BELLE}$, and the two new methods for accessing the helicity-dependent DiFFs both in the electron-positron annihilation experiments, and in the semi-inclusive deep inelastic scattering (SIDIS) experiments with a longitudinally polarized target. We will also for the first time describe yet another, new method for accessing the helicity-dependent DiFFs in SIDIS using polarized beam asymmetry. Finally, we will present a new Monte Carlo calculation of the specific Fourier moments of the helicity-dependent DiFF entering in to the new asymmetries, performed within the extended quark-jet model, and compare the results to those for the interference DiFF.