Electroweak Radiative Corrections to Neutral-Current Drell-Yan Processes at Hadron Colliders

TL;DR

This paper provides a complete calculation of electroweak O(α) corrections to neutral-current Drell–Yan processes at hadron colliders, separating QED and weak contributions and incorporating real photon emission, self-energies, vertices, and box diagrams within an on-shell renormalization framework. It demonstrates that weak corrections modestly enhance the Z cross section (~1%) in the resonance region and become large at high di-lepton masses due to Sudakov-like logarithms, while QED effects can significantly distort the invariant-mass spectrum near the Z and must be treated with detector-specific recombination and PDF factorization. The study introduces an effective Born approximation for the Z region and analyzes forward–backward asymmetries, showing small non-universal weak effects on A_FB near the Z peak but notable high-mass deviations and a threshold feature around m(ll) ≈ 160 GeV from WW box diagrams. The results highlight the need for EW corrections in precision SM tests and weak-mixing angle extractions at the Tevatron and LHC, and they emphasize that resummation of electroweak Sudakov logs will be essential for reliable predictions at multi-TeV scales.

Abstract

We calculate the complete electroweak O(alpha) corrections to pp, pbar p -> l+l- X (l=e, mu) in the Standard Model of electroweak interactions. They comprise weak and photonic virtual one-loop corrections as well as real photon radiation to the parton-level processes q bar q -> gamma,Z -> l+l-. We study in detail the effect of the radiative corrections on the l+l- invariant mass distribution, the cross section in the Z boson resonance region, and on the forward-backward asymmetry, A_FB, at the Fermilab Tevatron and the CERN Large Hadron Collider. The weak corrections are found to increase the Z boson cross section by about 1%, but have little effect on the forward-backward asymmetry in the Z peak region. Threshold effects of the W box diagrams lead to pronounced effects in A_FB at m(l+l-) approx 160 GeV which, however, will be difficult to observe experimentally. At high di-lepton invariant masses, the non-factorizable weak corrections are found to become large.

Figures (12)

• Figure 1: Born and higher-order weak contributions to $q\bar{q} \rightarrow \gamma,Z \to l^+ l^-$ in symbolic notation. The dark blob indicates the inclusion of all 1PI contributions to the photon and $Z$ propagators.
• Figure 2: Box diagrams contributing to $q\bar{q} \to l^+ l^-$.
• Figure 3: The relative corrections to the total cross sections for $u \bar{u} \to e^+ e^-$ and $d \bar{d} \to e^+ e^-$ a) in the vicinity of the $Z$ resonance, and b) at high parton center of mass energies.
• Figure 4: The relative corrections to the forward-backward asymmetry at parton level for $u\bar{u} \to e^+ e^-$ and $d \bar{d} \to e^+ e^-$ a) in the vicinity of the $Z$ resonance and b) at high parton center of mass energies.
• Figure 5: The relative corrections to the forward-backward asymmetry at the parton level in the region around the $W$-pair production threshold, $\sqrt{\hat{s}}=2 M_W$, for a) $u \bar{u} \to e^+ e^-$ and b) $d\bar{d} \to e^+ e^-$. The solid line shows $A_{\rm FB}-A_{\rm FB}^{\rm EBA}$ when the full set of Feynman diagrams contributing to the non-photonic weak corrections is taken into account. The dashed (dotted) lines show $A_{\rm FB}-A_{\rm FB}^{\rm EBA}$ when the $W$ ($Z$) box diagrams are disregarded.