Modeling Uncertainties on the Z Boson Background in the Context of High Precision W Boson Mass Measurements

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Main Authors: Boonekamp, Maarten, Schott, Matthias, Wang, Chen
Format: Preprint
Published: 2025
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author Boonekamp, Maarten
Schott, Matthias
Wang, Chen
author_facet Boonekamp, Maarten
Schott, Matthias
Wang, Chen
contents The precise determination of the $W$ boson mass, $m_W$, is a cornerstone of electroweak precision tests and a critical input to global fits of the Standard Model (SM). While most existing measurements of $m_W$ are in agreement with SM predictions, the recent result from the CDF collaboration exhibits a significant deviation from the SM prediction but also exceeding $4σ$ from the global average of all other high precision measurements. This prompts renewed scrutiny of potential sources of systematic bias. In this study, we investigate the modeling of the $Z$ boson background, which is particularly relevant in the muon decay channel of the $W$ boson, where undetected muons can mimic missing transverse momentum. Using updated theoretical predictions and high-precision simulations, we construct reweighted templates to evaluate the impact of possible mismodeling in the $Z$ background. Our analysis suggests that such effects can induce a shift in the extracted $m_W$ value of up to 8~MeV in the muon decay channel. While this shift is non-negligible and exceeds the originally quoted uncertainty from this source, it remains insufficient to explain the full discrepancy observed in the CDF measurement.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07835
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Modeling Uncertainties on the Z Boson Background in the Context of High Precision W Boson Mass Measurements
Boonekamp, Maarten
Schott, Matthias
Wang, Chen
High Energy Physics - Experiment
High Energy Physics - Phenomenology
The precise determination of the $W$ boson mass, $m_W$, is a cornerstone of electroweak precision tests and a critical input to global fits of the Standard Model (SM). While most existing measurements of $m_W$ are in agreement with SM predictions, the recent result from the CDF collaboration exhibits a significant deviation from the SM prediction but also exceeding $4σ$ from the global average of all other high precision measurements. This prompts renewed scrutiny of potential sources of systematic bias. In this study, we investigate the modeling of the $Z$ boson background, which is particularly relevant in the muon decay channel of the $W$ boson, where undetected muons can mimic missing transverse momentum. Using updated theoretical predictions and high-precision simulations, we construct reweighted templates to evaluate the impact of possible mismodeling in the $Z$ background. Our analysis suggests that such effects can induce a shift in the extracted $m_W$ value of up to 8~MeV in the muon decay channel. While this shift is non-negligible and exceeds the originally quoted uncertainty from this source, it remains insufficient to explain the full discrepancy observed in the CDF measurement.
title Modeling Uncertainties on the Z Boson Background in the Context of High Precision W Boson Mass Measurements
topic High Energy Physics - Experiment
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2507.07835