The W boson might not be heavier than expected after all

The particle’s mass is an important test of the standard model of particle physics

A photo from the ATLAS experiment at CERN's Large Hadron Collider.

A fresh analysis of W boson measurements from the ATLAS experiment (pictured) at CERN’s Large Hadron Collider is in close agreement with theory and at odds with a heavy W boson mass announced last year.

Maximilien Brice/CERN

The battle over the heft of a hard-to-detect particle is heating up.