Fonctionne avec Indico
v3.2.8
Within the Standard Model of particle physics, the electroweak spontaneous symmetry breaking mechanism is responsible for the appearance of a longitudinal polarisation state in the massive W± and Z vector bosons. The study of polarisation states in diboson processes, corresponding to the pair production of two such vector bosons, constitutes a detailed test of the Standard Model as it allows to probe indirectly this symmetry breaking mechanism. The ATLAS and CMS collaborations have performed single boson polarisation measurements in the W± Z pair production, a channel of choice for such measurements. This talk will specifically discuss the joint-polarisation measurement I performed during my PhD. Using data recorded by the ATLAS detector during the Run 2 of the LHC, corresponding to an integrated luminosity of 139 fb−1 of proton-proton collisions at a centre-of-mass energy of 13 TeV, joint-polarisation fractions in W± Z production were measured, leading to the the first ever observation of two bosons produced simultaneously with a longitudinal polarisation. Single boson polarisation fractions of the W and Z bosons were also measured and found to be consistent with joint-polarisation fractions within the expected amount of correlations.