News

Following nearly a decade of analysis, the CMS experiment has found that the W boson’s mass aligns perfectly with Standard Model predictions with remarkable accuracy.

Physicists on the CMS experiment announce the most elaborate mass measurement of a particle that is notoriously difficult to study and has captivated the physics community for decades.

The ATLAS collaboration measured the W-boson width at the LHC for the first time. The W-boson width had previously been measured at CERN’s LEP collider and Fermilab’s Tevatron collider. This is the most precise measurement to date made by a single experiment, and—while a bit larger—it is consistent with the Standard-Model prediction to within 2.5 standard deviations.

From New Scientist, Dec. 16, 2022: This year was another busy year in science and technology and New Scientist news editors’ have chosen some of the biggest scientific developments, discoveries and events in 2022. Included in this year’s selections is the April 2022 announcement of the mass of the W boson that used Fermilab’s Tevatron.

From Science News, August 15, 2022: W bosons are particles that transmit the weak force, which is responsible for certain types of radioactive decay. Last April, Fermilab researchers reported the W boson was more massive than predicted, hinting that something may be amiss with the standard model. Now a team of scientists with ATLAS at the LHC are reporting rare boson triplets which continues to test the standard model for any cracks.

From PBS Space Time, May 25, 2022: Fermilab scientists spent almost a decade recording collisions in the Tevatron collider and another ten years analyzing data finding the W boson’s mass seems to be 0.01 percent heavier than expected. Now, understanding why the particle has mass puts the current Standard Model to the test.

From MSN (Spain), May 26, 2022: A series of precise measurements of well-known ordinary particles and processes have threatened to shake our understanding of physics from the Muon g-2 and W boson Fermilab announcements . Now the LHC is preparing to operate at a higher energy level and intensity than ever before, there is a chance that new particles are produced through even rarer processes or are hidden under backgrounds that we have not yet unearthed.

The CDF experiment at Fermilab measured the mass of the W boson and came up with an answer that no one expected.

From Nature Italy May 20, 2022: CDF co-spokesperson Giorgio Chiarelli tells the story of how Italy contributed to the measurement of the W boson mass, opening a door on new physics. For more than 10 years after the Tevatron detector at Fermilab produced the last crashes between protons and antiprotons, the collaboration announced the most precise measure of the W boson mass ever achieved.

From the Nature Briefing, May 13, 2022: Based on data recorded with the CDF II detector at Fermilab between 2002 and 2011 at the Tevatron, the collaboration reconstructed more than 4 million W boson candidates through their decays into an electron or muon accompanied by the respective neutrino. The CDF Collaboration stated their result “suggests the possibility of improvements to the standard model calculation or of extensions to it”.