Dihadron fragmentation functions in the quark-jet model: Longitudinally polarized quarks

TL;DR

This paper investigates the dihadron fragmentation functions of longitudinally polarized quarks using a quark-jet model, revealing a nonzero helicity-dependent function and developing methods to extract relevant asymmetries in high-energy processes.

Contribution

It introduces a Monte Carlo simulation approach to study helicity-dependent dihadron fragmentation functions within the quark-jet model, including new extraction methods for angular moments.

Findings

Nonvanishing helicity-dependent DiFF $G_1^ot$ found

Developed a method to extract angular moments of DiFFs

Validated Monte Carlo results with explicit integral expressions

Abstract

We study the dihadron fragmentation functions (DiFF) of longitudinally polarized quarks into pion pairs. The quark-jet framework is used to model the sequential hadronization of a polarized quark into hadrons, where the polarization transfer to the remnant quark in each hadron emission step is calculated using the spin density matrix formalism. Using Monte Carlo (MC) simulations of the hadronization process, we find a nonvanishing helicity dependent DiFF, $G_1^\perp$ , which is also related to the longitudinal jet handedness. A method is developed for extracting the angular moments of this DiFF, which enter the expressions for the azimuthal asymmetries for an electron-positron annihilation process into two pairs of hadrons from back-to-back jets and the dihadron production in semi-inclusive deep inelastic scattering. Finally, we derive explicit integral expressions for DiFFs where only two hadrons are emitted by a quark and use them to validate our MC results for both unpolarized and helicity dependent DiFFs.