Work

Lam-Tung relation breaking in Z boson production as a probe of standard model effective field theory effects

Year: 2025

Type: article

Abstract: The violation of the Lam-Tung relation in the high- p T ℓ ℓ region of the Drell-Yan process at the LHC presents a longstanding discrepancy with the standard model prediction at O ( α s 3 ) accuracy. In this paper, we employed a model-independent analysis to investigate this phenomenon within the framework of the standard model effective field theory (SMEFT). Our findings revealed that the leading contributions from SMEFT to this violation appear at the 1 / Λ 4 order with O ( α s ) accuracy in quantum chromodynamics (QCD) interaction. Notably, we demonstrated that the quadratic effect of dimension-6 dipole operators, associated with the Z boson, dominates the breaking effects induced by various dimension-6 and dimension-8 operators. This provides a possible explanation for the observed discrepancy with the Standard Model predictions at the LHC. Furthermore, the breaking effects could also serve as a powerful tool for constraining Z -boson dipole interactions, highlighting their importance among potential sources of new physics in the Drell-Yan process.

Source: Physical review. D/Physical review. D.

DOI: 10.1103/physrevd.111.073007

Authors: Xu Li, Bin Yan, C.-P. Yuan

Institutions: Chinese Academy of Sciences, Institute of High Energy Physics, University of Chinese Academy of Sciences, Michigan State University

Language: English

Topic: Particle physics theoretical and experimental studies

Subfield: Nuclear and High Energy Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Funders: National Science Foundation, National Natural Science Foundation of China, Chinese Academy of Sciences, Institute of High Energy Physics