Upsilon production at the Tevatron and the LHC

TL;DR

This paper refines theoretical predictions for Upsilon production at high-energy colliders using NRQCD, highlighting the importance of higher-order corrections and challenging the necessity of color-octet mechanisms.

Contribution

It provides the first detailed calculation of alpha_s^5 contributions to Upsilon production, showing they align well with experimental data and suggesting color-octet contributions may be unnecessary.

Findings

Next-to-leading order corrections increase high pT cross sections.

Alpha_s^5 contributions from associated light partons match data.

Upsilon polarization is predicted to be longitudinal.

Abstract

We update the theoretical predictions for direct Y(nS) hadroproduction in the framework of NRQCD. We show that the next-to-leading order corrections in alpha_s to the color-singlet transition significantly raise the differential cross section at high pT and substantially affect the polarization of the Upsilon. Motivated by the remaining gap between the NLO yield and the cross section measurements at the Tevatron, we evaluate the leading part of the alpha_s^5 contributions, namely those coming from Y(nS) associated with three light partons. The differential color-singlet cross section at alpha_s^5 is in substantial agreement with the data, so that there is no evidence for the need of color-octet contributions. Furthermore, we find that the polarization of the Y(nS) is longitudinal. We also present our predictions for Y(nS) production at the LHC.