[Paper Review] Electroweak Physics: Theoretical Overview

Doreen Wackeroth|ArXiv.org|Oct 4, 2006

Particle physics theoretical and experimental studies31 references3 citations

TL;DR

This paper provides a comprehensive theoretical overview of electroweak physics at hadron colliders, focusing on precision predictions for single W and Z boson production. It emphasizes the critical role of electroweak radiative corrections in enabling accurate measurements of the W boson mass and width, which are essential for testing the Standard Model and probing physics beyond the Standard Model at the Tevatron and LHC.

ABSTRACT

I give an overview of the theory status of predictions for single W and Z boson production at hadron colliders. I briefly report on work in progress for improvements necessary to match the anticipated high precision of electroweak measurements, such as the W mass and width, at the Fermilab Tevatron p anti-p and the CERN LHC pp colliders.

Motivation & Objective

• To assess the theoretical precision required to match the high experimental accuracy expected at the Tevatron and LHC for electroweak observables.
• To evaluate the impact of electroweak radiative corrections on W and Z boson measurements, particularly in the context of W mass and width extraction.
• To identify gaps in current theoretical calculations and determine whether further improvements are needed to avoid misinterpreting higher-order corrections as new physics.
• To advance the development of unified Monte Carlo programs that include QCD, QED, and electroweak corrections for realistic simulation of W and Z boson observables.
• To support the TeV4LHC working group in establishing a benchmark for theoretical uncertainties in W and Z production predictions.

Proposed method

• Utilizing next-to-next-to-leading order (NNLO) QCD and next-to-leading order (NLO) electroweak corrections to compute fully differential cross sections for W and Z boson production.
• Applying all-order resummation of soft gluon radiation to improve the description of the W boson transverse momentum distribution.
• Incorporating full electroweak O(α) corrections, including weak non-resonant and real two-photon radiation effects, to model final-state radiation and its impact on M_T distributions.
• Comparing results from multiple independent Monte Carlo programs to ensure consistency and reduce theoretical uncertainties.
• Investigating combined QCD and electroweak corrections, Sudakov logarithms, and multiple final-state photon radiation to assess their relevance at LHC precision.
• Working toward a unified Monte Carlo framework that integrates QCD, QED, and electroweak corrections, including mixed ααs two-loop corrections not yet available.

Experimental results

Research questions

• RQ1 What is the residual theoretical uncertainty in current predictions for W and Z boson production at hadron colliders?
• RQ2 To what extent do electroweak radiative corrections affect the extraction of the W boson mass and width from transverse mass distributions?
• RQ3 Can higher-order electroweak corrections be mistaken for signals of new physics, such as anomalous triple gauge couplings?
• RQ4 What improvements are necessary in theoretical calculations to fully exploit the electroweak precision physics potential of the Tevatron and LHC?
• RQ5 How can a unified Monte Carlo program be developed to include all relevant QCD, QED, and electroweak corrections for precision physics?

Key findings

• Electroweak radiative corrections of O(α) can shift the W boson mass by up to ~10 MeV and affect the width by ~7 MeV, comparable in magnitude to potential new physics signals.
• Real two-photon radiation and multiple final-state photon emissions shift the W mass by 2–10 MeV depending on the final state, with significant impact on the M_T distribution shape.
• Without proper inclusion of electroweak corrections, experimental deviations in the W boson mass or width could be misinterpreted as evidence of new physics.
• For LHC-level precision (δM_W ≈ 15 MeV), theoretical uncertainties from missing higher-order corrections must be controlled to better than ~5 MeV to avoid biasing indirect Higgs boson mass bounds.
• Combined QCD and electroweak corrections, Sudakov logarithms, and multiple photon radiation effects are expected to be significant at LHC precision and must be included in data analysis.
• Ongoing efforts aim to unify QCD, QED, and electroweak corrections in a single Monte Carlo program to achieve the required theoretical accuracy for future electroweak precision measurements.