Collins asymmetries in inclusive charged $KK$ and $K\pi$ pairs produced in $e^+e^-$ annihilation

TL;DR

This paper reports measurements of Collins asymmetries in inclusive charged kaon and pion pairs produced in electron-positron annihilation at 10.6 GeV, revealing azimuthal asymmetries that increase with hadron energies and vary among different hadron pairs.

Contribution

First measurement of Collins asymmetries in inclusive $KK$, $K ext{pi}$, and $ ext{pi} ext{pi}$ pairs at 10.6 GeV using BaBar data, highlighting differences among hadron pair types.

Findings

Clear azimuthal asymmetries observed in hadron pairs.

Asymmetries increase with hadron energy.

$KK$ asymmetries are generally larger than $K ext{pi}$ and $ ext{pi} ext{pi}$.

Abstract

We present measurements of Collins asymmetries in the inclusive process $e^+e^- \rightarrow h_1 h_2 X$, $h_1h_2=KK,\, K\pi,\, \pi\pi$, at the center-of-mass energy of 10.6 GeV, using a data sample of 468 fb$^{-1}$ collected by the BaBar experiment at the PEP-II $B$ factory at SLAC National Accelerator Center. Considering hadrons in opposite thrust hemispheres of hadronic events, we observe clear azimuthal asymmetries in the ratio of unlike- to like-sign, and unlike- to all charged $h_1 h_2$ pairs, which increase with hadron energies. The $K\pi$ asymmetries are similar to those measured for the $\pi\pi$ pairs, whereas those measured for high-energy $KK$ pairs are, in general, larger.