Physicists re-analyzed a sample of W bosons recorded in 2011 by the ATLAS detector installed by the
In 2017, the ATLAS experiment teampresented the first measurement of W boson mass, based on a sample of W bosons detected by ATLAS in 2011. The mass of the W boson then turned out to be 80,370 MeV with an error of 19 MeV.
To improve the accuracy of the result, physicistsreanalyzed data on 14 million W-boson candidate events. They used advanced data fitting techniques to determine the mass, as well as refined parton proton distribution functions. They describe the distribution of the momentum of a proton among its constituent quarks and gluons. In addition, ATLAS tested the theoretical description of the W-boson production process using special LHC proton-proton cycles.
The electrically charged W-boson and electricallythe neutral Z-boson are the carriers of the weak interaction. This is one of the fundamental types of interaction that is responsible for the radioactive decay of atomic nuclei and initiates the nuclear fusion reaction that powers the stars. These particles were discovered at CERN in 1983 and helped validate the theory of the electroweak force, which unifies the electromagnetic force and the weak force.
In the Standard Model of particle physicsThe mass of the W boson is closely related to the strength of the electroweak interactions and the masses of the heaviest fundamental particles, including the Z boson, top quark, and Higgs boson. In this theory, the particle should weigh 80,354 MeV with an error of 7 MeV.
Any deviation of the measured mass from the predictionThe Standard Model will be an indicator of new physical phenomena, new particles or interactions. Therefore, accurate measurement of mass is extremely important for experiments.
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Cover image: ATLAS experiment