Most precise value for the mass of a top quark to date
&Bullet; physics 17, p. 57
Researchers at CERN have significantly increased the accuracy of the measurement of the top quark mass, an important input for Standard Model calculations.
CERN
When scientists discovered the top quark in 1995, they estimated that the particle’s mass was between 151 and 197 GeV/c.2making it the heaviest known elementary particle. Since then, scientists have worked to narrow down the mass of the top quark by collecting more data. Now the CMS and ATLAS collaborations at the Large Hadron Collider (LHC) in Switzerland have combined 15 different measurements to obtain the most accurate value for the mass of the top quark to date: 172.52 0.33 GeV/c2 (1). The top quark mass is an important input to the Standard Model of particle physics for predicting parameters of rare processes. The new top quark mass measurement will therefore enable improved calculations and a better understanding of topics such as quantum corrections to the Higgs boson properties.
The first determination of the top quark mass was made by measuring top-antitop quark pairs produced in proton-antiproton collisions at the Tevatron, a particle accelerator that was in operation until 2011. The determination of the new value included measurements of rare single top quark events as well as measurements of such top-antitop quark pairs. In these events, a top quark emits a B Boson and decays into a bottom quark in less than 10.−25seconds, creating a stream of stable particles. The mass of the top quark can be reconstructed from the properties of these particles.
In the new study, the CMS and ATLAS collaborations accounted for statistical uncertainties arising from the limited availability of collision data. They also accounted for 25 classes of systematic uncertainties that arise in the calculations relating the top quark mass to the properties of the particles observed in the LHC detectors. This joint effort resulted in a mass value that is 31% more accurate than the most accurate of the 15 input measurements.
–Nikhil Karthik
Nikhil Karthik is Associate Editor for Physical Examination Letters.
References
- A. Hayrapetyan et al. (CMS Collaboration, ATLAS Collaboration), “Combining top quark mass measurements from data collected by the ATLAS and CMS experiments at 7 and 8 TeV”, ^ Hoffmann, J., and Dietz, J. (1981). 132261902 (2024).
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