Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Effects of QCD Resummation on Distributions of Leptons from the Decay of Electroweak Vector Bosons

Csaba Balazs, Jianwei Qiu, C. --P. Yuan

TL;DR

This work demonstrates that initial-state soft-gluon emissions in hadron collisions significantly affect leptonic distributions from electroweak vector boson decays. By applying the Collins-Soper resummation formalism, it provides a fully differential QCD prediction incorporating a Sudakov form factor and a non-perturbative function, complemented by a Y-term, to accurately model p_T^l, y^l, and Δφ observables. Numerical results for Tevatron W production show that resummation smooths the Jacobian peak in p_T^l, stabilizes angular correlations, and improves lepton asymmetry predictions compared with fixed-order NLO. The study highlights the necessity of resummation for precision W-mass measurements and for reliable lepton-kinematics modeling in hadron-collider analyses.

Abstract

We study the distributions of leptons from the decay of electroweak vector bosons produced in hadron collisions. The effects of the initial state multiple soft-gluon emission, using the Collins--Soper resummation formalism, are included. The resummed results are compared with the next-to-leading-order results for the distributions of the transverse momentum, rapidity asymmetry, and azimuthal angle of the decay leptons.

Effects of QCD Resummation on Distributions of Leptons from the Decay of Electroweak Vector Bosons

TL;DR

This work demonstrates that initial-state soft-gluon emissions in hadron collisions significantly affect leptonic distributions from electroweak vector boson decays. By applying the Collins-Soper resummation formalism, it provides a fully differential QCD prediction incorporating a Sudakov form factor and a non-perturbative function, complemented by a Y-term, to accurately model p_T^l, y^l, and Δφ observables. Numerical results for Tevatron W production show that resummation smooths the Jacobian peak in p_T^l, stabilizes angular correlations, and improves lepton asymmetry predictions compared with fixed-order NLO. The study highlights the necessity of resummation for precision W-mass measurements and for reliable lepton-kinematics modeling in hadron-collider analyses.

Abstract

We study the distributions of leptons from the decay of electroweak vector bosons produced in hadron collisions. The effects of the initial state multiple soft-gluon emission, using the Collins--Soper resummation formalism, are included. The resummed results are compared with the next-to-leading-order results for the distributions of the transverse momentum, rapidity asymmetry, and azimuthal angle of the decay leptons.

Paper Structure

This paper contains 3 sections, 20 equations, 3 figures.

Table of Contents

  1. Introduction
  2. The Resummation Formalism
  3. Numerical Results

Figures (3)

  • Figure 1: Transverse momentum distribution of the charged lepton $p_T^\ell$ for NLO (dashed) and resummed (solid) calculations. Resumming the initial state multiple soft-gluon emission has the typical effect of smoothening and widening the Jacobian peak (at $p_T^\ell = M_W/2$). The NLO distribution is singular and ill-defined near $M_W/2$.
  • Figure 2: The asymmetry ${\cal A}_{y^\ell}$ in the lepton rapidity distribution as a function of ${y^\ell}$ for NLO (dashed) and resummed (solid) calculations. They differ the most in the large rapidity region ($|y_{\ell^+}| > 1$). The experimental data were obtained from Ref. [15]
  • Figure 3: The distribution of the difference in the lepton azimuthal angles near the region $\Delta \phi \sim \pi$. The NLO (dashed) distribution is ill-defined at $\Delta \phi = \pi$ and is arbitrary around it. The resummed (solid) distribution gives the correct angular correlation of the lepton pair. The distribution has a similar peak for $\Delta \phi \sim -\pi$.