(AGENPARL) - Roma, 17 Settembre 2024 - (AGENPARL) – mar 17 settembre 2024 CERN PRESS RELEASE
CMS experiment at CERN weighs in on the W boson mass
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CMS candidate collision event for a W boson decaying into a muon (red line) and a neutrino that escapes detection (pink arrow). (Image: CMS/CERN)
The eagerly awaited result is the most precise measurement of the W mass made at the LHC so far, and is in line with the prediction from the Standard Model of particle physics
Measuring the W boson mass with high precision therefore makes it possible to test whether or not these properties all align in a way that is consistent with the Standard Model. If they don’t, the cause could be new physics phenomena such as new particles or interactions.
The CMS experiment has now contributed to this global endeavour with its first W boson mass measurement. The keenly anticipated result, 80360.2 with an uncertainty of 9.9 MeV, has a precision comparable to that of the CDF measurement and is in line with all previous measurements except the CDF result.
“The wait for the CMS result is now over. After carefully analysing data collected in 2016 and going through all the cross checks, the CMS W mass result is ready,” says outgoing CMS spokesperson Patricia McBride. “This analysis is the first attempt to measure the W mass in the harsh collision environment of the second running period of the LHC. And all the hard work from the team has resulted in an extremely precise W mass measurement and the most precise measurement at the LHC.”
“W mass measurements are very challenging, involving delicate measurements and theoretical modelling of the production of the W boson and its decay into a lepton (here, a muon) and a neutrino that escapes detection,” explains incoming CMS spokesperson Gautier Hamel de Monchenault. “By exploiting the ability of the CMS detector to measure muons with high precision and using the latest and most advanced theoretical ingredients, some of which were tested by a cross-checking analysis, we attained this record level of precision.”
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Measurements of the W boson mass reported over the years by experiments worldwide. The CMS measurement is the most precise one made at the LHC so far, and has a precision comparable to that of the CDF measurement. (Image: CMS/CERN)
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