W Boson Mass Discrepancy Sparks Physics Debate

The mass of the W boson, a fundamental particle crucial for nuclear fusion, is at the center of a scientific debate following conflicting experimental results.In 2023, a team led by Duke University physicist Ashutosh Kotwal analyzed data from the Fermi National Accelerator Laboratory near Chicago, suggesting the W boson was significantly heavier than predicted by the Standard Model of particle physics. Their measurement, based on the CDF experiment involving four million W bosons, indicated a mass of 77 million electron volts (eV) higher than the theoretical value, with a margin of error of only 0.01%.However, a subsequent measurement by researchers at CERN's Large Hadron Collider in Switzerland contradicted these findings. The CERN experiment, using the CMS detector, aligned with the mass predicted by the Standard Model, effectively nullifying the anomaly.This discrepancy raises concerns about potential flaws in the experimental techniques or overlooked sources of error. Kotwal's recent study, published in Physical Review Research in February 2025, scrutinizes the calculations used in the Fermilab experiment. The study focuses on the precise measurement of particle trajectories within the CDF detector, a can-shaped chamber containing 30,240 high-voltage wires. Kotwal's team meticulously examined potential wire misalignments that could skew the results.Despite the rigorous analysis, Kotwal concluded that even accounting for minuscule wire shifts, the particle's kinetic energy measurement remains accurate to 25 parts per million. "From this perspective, the CDF measurement checks out," Kotwal stated.The ongoing investigation aims to identify the source of the discrepancy between the two experiments. Kotwal emphasizes the importance of transparency in scientific methods, urging other experiments to conduct similar internal audits. The resolution of this mass mystery could lead to a deeper understanding of the fundamental laws of nature and potentially reveal cracks in the Standard Model of particle physics.