Resummation prediction on top quark transverse momentum distribution at large pT

TL;DR

This paper applies soft-collinear effective theory to improve predictions of the top quark transverse momentum distribution at large pT, showing resummation effects increase NLO results and analyzing scale choices for better convergence.

Contribution

It calculates NLO soft functions and provides a RG improved cross section for top quark pT distribution at large pT in the SM at Tevatron and LHC.

Findings

Resummation increases NLO results by 9%-13% at Tevatron and 4%-9% at LHC.

Resummation effects are significant for large pT (>50 GeV).

Proper scale choices improve perturbative convergence.

Abstract

We study the factorization and resummation of t-channel top quark transverse momentum distribution at large pT in the SM at both the Tevatron and the LHC with soft-collinear effective theory. The cross section in the threshold region can be factorized into a convolution of hard, jet and soft functions. In particular, we first calculate the NLO soft functions for this process, and give a RG improved cross section by evolving the different functions to a common scale. Our results show that the resummation effects increase the NLO results by about 9%-13% and 4%-9% when the top quark pT is larger than 50 and 70 GeV at the Tevatron and the 8 TeV LHC, respectively. Also, we discuss the scale independence of the cross section analytically, and show how to choose the proper scales at which the perturbative expansion can converge fast.