Enlarge / Occasion show of a W-boson candidate decaying right into a muon and a muon neutrino contained in the ATLAS experiment. The blue line exhibits the reconstructed monitor of the muon, and the purple arrow denotes the vitality of the undetected muon neutrino. (credit score: ATLAS Collaboration/CERN)
It is usually stated in science that extraordinary claims require extraordinary proof. Current measurements of the mass of the elementary particle often called the W boson present a helpful case examine as to why. Final yr, Fermilab physicists brought on a stir after they reported a W boson mass measurement that deviated fairly considerably from theoretical predictions of the so-called Commonplace Mannequin of Particle Physics—a tantalizing trace of recent physics. Others suggested warning, because the measurement contradicted prior measurements.
That warning seems to have been warranted. The ATLAS collaboration at CERN’s Massive Hadron Collider (LHC) has introduced a brand new, improved evaluation of their very own W boson information and located the measured worth for its mass was nonetheless per Commonplace Mannequin. Caveat: It is a preliminary outcome. However it lessens the chance of Fermilab’s 2022 measurement being appropriate.
“The W mass measurement is among the many most difficult precision measurements carried out at hadron colliders,” stated ATLAS spokesperson Andreas Hoecker. “It requires extraordinarily correct calibration of the measured particle energies and momenta, and a cautious evaluation and glorious management of modeling uncertainties. This up to date outcome from ATLAS gives a stringent take a look at, and confirms the consistency of our theoretical understanding of electroweak interactions.”
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