[Paper Review] Combination of CDF and D0 Results on the Mass of the Top Quark

D Collaborations|arXiv (Cornell University)|Jul 19, 2010

Particle physics theoretical and experimental studies18 references298 citations

TL;DR

This paper combines top-quark mass measurements from CDF and D0 experiments at Fermilab's Tevatron collider, integrating Run I (1992–1996) and Run II (2001–present) data up to 5.6 fb⁻¹. By properly accounting for uncertainty correlations and combining statistical and systematic uncertainties in quadrature, the study reports a preliminary average top quark mass of 173.3 ± 1.1 GeV/c².

ABSTRACT

We summarize the top-quark mass measurements from the CDF and DO experiments at Fermilab. We combine published Run I (1992-1996) measurements with the most precise published and preliminary Run II (2001-present) measurements using up to 5.6fb-1 of data. Taking uncertainty correlations properly into account, and adding in quadrature the statistical and systematic uncertainties, the resulting preliminary Tevatron average mass of the top quark is M(top) = 173.3+-1.1.

Motivation & Objective

• To improve the precision of the top quark mass measurement by combining results from two major Tevatron experiments, CDF and D0.
• To incorporate both published Run I and the most precise published and preliminary Run II measurements into a single, consistent average.
• To account for correlations between systematic and statistical uncertainties in the combination process to ensure accurate error propagation.
• To provide a definitive, high-precision estimate of the top quark mass based on the full Tevatron dataset available at the time.

Proposed method

• The analysis combines published Run I measurements from CDF and D0 with the most precise published and preliminary Run II measurements from both experiments.
• Uncertainty correlations between the measurements are explicitly modeled and accounted for in the combination to avoid double-counting systematic effects.
• Statistical and systematic uncertainties are combined in quadrature to determine the total uncertainty of the final result.
• The final average mass is computed using a weighted mean approach that reflects the relative precision of each individual measurement.
• The dataset used spans up to 5.6 fb⁻¹ of integrated luminosity from proton-antiproton collisions at √s = 1.96 TeV.
• The combination procedure ensures consistency and minimizes bias by applying standard error propagation techniques to correlated uncertainties.

Experimental results

Research questions

• RQ1 What is the most precise average value of the top quark mass based on the full Tevatron dataset from Run I and Run II?
• RQ2 How do correlations between systematic uncertainties across CDF and D0 measurements affect the final combined uncertainty?
• RQ3 To what extent does including preliminary Run II results improve the precision of the top quark mass measurement compared to Run I alone?
• RQ4 What is the impact of combining data from two independent experiments on the overall uncertainty of the top quark mass?

Key findings

• The combined analysis yields a preliminary average top quark mass of 173.3 ± 1.1 GeV/c², representing a significant improvement in precision over individual measurements.
• The uncertainty in the final result is dominated by systematic effects, which were carefully correlated across CDF and D0 measurements.
• The inclusion of Run II data, particularly up to 5.6 fb⁻¹ of integrated luminosity, significantly reduced the statistical uncertainty compared to Run I alone.
• The final result reflects a consistent and robust combination of both published and preliminary measurements from both experiments.
• The uncertainty correlation treatment ensures that the combined uncertainty is not underestimated, preserving the validity of the error estimate.
• The result is consistent with the standard model prediction and provides a critical input for precision tests of electroweak theory.