Transverse Momentum Distributions in the Non-Perturbative Region

TL;DR

This paper investigates the low transverse momentum distribution of Z-bosons at hadron colliders near the non-perturbative scale, introducing a new gauge-invariant transverse momentum function within SCET to model non-perturbative effects.

Contribution

It proposes a novel non-perturbative transverse momentum function (TMF) in SCET that captures effects beyond standard parton distributions in the low p_T region.

Findings

Developed phenomenological models for TMFs

Fitted models to experimental data

Demonstrated TMF reduces to perturbative results at high p_T

Abstract

We study the low transverse momentum (p_T) distribution of the Z-boson at hadron colliders for p_T ~ Lambda_{QCD} using a factorization and resummation formula derived in the Soft Collinear Effective Theory (SCET). In the region p_T ~ Lambda_{QCD}, new non-perturbative effects arise that cannot be entirely captured by the standard parton distribution functions, and require an additional new non-perturbative transverse momentum function (TMF). The TMF is field-theoretically defined in SCET, fully gauge invariant, and captures the non-perturbative dynamics that affects the p_T-distribution in the region p_T ~ Lambda_{QCD}. The TMF also reduces to the expected perturbative result in the region p_T >> Lambda_{QCD}. We develop phenomenological models for these TMFs in the non-perturbative region and present example fits to the available data.