Seminar: Nenad Vranješ, 13 March 2017

Measurement of the W-boson mass with the ATLAS detector

We will present results of the W-boson mass (mW) measurement from the Large Hadron Collider (LHC) recently published by ATLAS Collaboration [1]. Precise determination of the mW is of high importance for testing the overall consistency of the Standard Model (SM). In the context of global fits to the SM parameters, constraints on physics beyond the SM are currently limited by the measurement of the W-boson mass. Measurement is performed using about 8 million W?µ? and about 6 million W?e? candidates from the proton-proton collisions data recorded in 2011 at a centre-of-mass energy of 7 TeV with the ATLAS, and it is the first measurement of the mW at the LHC. The measured value yields:

mW = 80370 ± 7 (stat.) ± 11 (exp. sys.) ± 14 (mod. sys.) MeV = 80370 ± 19 MeV,

where the first uncertainty is statistical, the second corresponds to the experimental systematic uncertainty, and the third to the physics-modelling systematic uncertainty. The results matches the precision reached by CDF and D0 experiments from the Tevatron collider. The central value is consistent with both current world average and theoretical predictions. We will discuss the measurement challenges, analyse key systematic uncertainties and comment on possible improvements with LHC data.

[1] ATLAS Collaboration, arXiv:1701.07240 [hep-ex], submitted to EPJC.