Upsilonium Polarization as a Touchstone in Understanding the Parton Dynamics in QCD

TL;DR

This paper investigates Upsilon meson production and polarization at Fermilab Tevatron within the $k_T$-factorization framework, proposing polarization measurements as key tests to distinguish between competing QCD models.

Contribution

It introduces the use of Upsilon polarization as a diagnostic tool to differentiate theoretical approaches to parton dynamics in QCD.

Findings

Calculated $p_T$-distributions agree with D0 data

Polarization measurements can discriminate between models

Highlights importance of double cross section measurements

Abstract

In the framework of the $k_T$-factorization approach, the production of Upsilon mesons at the Fermilab Tevatron is considered, and the comparisions of calculated $p_T$-distributions and spin alignment parameter $\alpha$ with the D0 experimental data are shown. We argue that measuring the double cross section and the polarization of upsilonium states can serve as a crucial test discriminating two competing theoretical approaches to parton dynamics in QCD.