Status of the Upsilon Polarization Measurement at CDF

TL;DR

This paper reports on the measurement of Upsilon(1S) polarization at CDF, finding potential longitudinal polarization at high transverse momentum, which challenges existing NRQCD predictions.

Contribution

It provides the first detailed angular analysis of Upsilon(1S) polarization at Tevatron energies, highlighting discrepancies with theoretical models.

Findings

Upsilon(1S) may be longitudinally polarized at high p_T

Results are inconsistent with NRQCD predictions of transverse polarization

Analysis uses 2.9 fb^{-1} of data at sqrt{s} = 1.96 TeV

Abstract

The angular distributions of Upsilon(1S) to mu+ mu- decays are analyzed using a sample of Upsilon(1S) mesons in 2.9 fb^{-1} of data collected at sqrt{s} = 1.96TeV. The results of the one-dimensional angular analysis suggest that Upsilon(1S) may be longitudinal polarized at high transverse momentum. This observation is largely inconsistent with NRQCD prediction that predicts transverse polarization at high p_T.