Measurement of Collins asymmetries in inclusive production of pion pairs in e^+e^- collisions at BABAR

TL;DR

This paper reports a measurement of Collins asymmetries in pion pair production from electron-positron collisions at BABAR, confirming a non-zero effect and analyzing its dependence on kinematic variables.

Contribution

First measurement of Collins asymmetries in inclusive pion pair production at BABAR, exploring their dependence on energy, momentum, and angle.

Findings

Confirmed non-zero Collins asymmetry consistent with previous experiments

Analyzed asymmetry dependence on pion fractional energies and transverse momenta

Provided detailed angular dependence of the Collins effect

Abstract

We present a preliminary measurement of the Collins asymmetries in the inclusive process e^+e^- --> qqbar --> pi pi X at center-of-mass energy near 10.6 GeV. We use a data sample of 468 fb^(-1) collected by the BABAR experiment, and we consider pairs of charged pions produced in opposite jets in hadronic events. We confirm a non-zero Collins effect as observed by previous experiments, and we study the Collins asymmetry as a function of pion fractional energies and transverse momenta, and as a function of the polar angle of the analysis axis.