Precise test of lepton flavour universality in W -boson decays into muons and electrons in pp collisions at s = 13 Te V with the ATLAS detector

Journal article

The ratio of branching ratios of the W boson to muons and electrons, RWμ/e=B(W→μν)/B(W→eν), has been measured using 140fb-1 of pp collision data at s=13 TeV collected with the ATLAS detector at the LHC, probing the universality of lepton couplings. The ratio is obtained from measurements of the tt¯ production cross-section in the ee, eμ and μμ dilepton final states. To reduce systematic uncertainties, it is normalised by the square root of the corresponding ratio RZμμ/ee for the Z boson measured in inclusive Z→ee and Z→μμ events. By using the precise value of RZμμ/ee determined from e+e- colliders, the ratio RWμ/e is determined to be RWμ/e=0.9995±0.0022(stat)±0.0036(syst)±0.0014(ext).The three uncertainties correspond to data statistics, experimental systematics and the external measurement of RZμμ/ee, giving a total uncertainty of 0.0045, and confirming the Standard Model assumption of lepton flavour universality in W-boson decays at the 0.5% level.

Authors: Aad, G; Aakvaag, E; Abbott, B; Abdelhameed, S; Abeling, K

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: SpringerOpen
• Journal: The European Physical Journal C
• Volume: 84
• Issue: 10
• Article number: 993
• Publication date: 2024-10-01
• Acceptance date: 2024-06-29
• DOI: 10.1140/epjc/s10052-024-13070-4
• EISSN: 1434-6052
• Language: English