Study of W^±Z longitudinal-longitudinal interactions (𝑊^±₀Ζ₀) with Full Leptonic Final States (W^±Ζ→ι^±νι^±ι^∓) in ρρ collisions at √s=13 TeV with the ATLAS detector

In the Standard Model of particle physics, the spontaneous symmetry breaking of the complex Higgs field gives rise to the massive Higgs boson and three Goldstone bosons, which represent the longitudinal degree of freedom of the 𝑊^± and 𝑍 bosons. It is therefore critical to study the interactions of longitudinally-polarized 𝑊^± and 𝑍 bosons (𝑊^±₀ and 𝑍₀). Here, we present the first such analysis, in inclusive fully-leptonic final states (𝑊^±𝑍→𝑙^±ν𝑙^±𝑙^∓) with 139 fb⁻¹ of p-p collision data recorded with the ATLAS detector at 13 TeV of center of mass energy. We use kinematic variables like p_T^Zand p_T^𝑊±𝑍 to enhance the 𝑊^±₀𝑍₀ contribution. The so called radiation amplitude zero effect also enhances the 𝑊^±₀𝑍₀ contribution in the central region (cos𝜃_𝑉 ~ 0, where 𝜃_𝑉 is the scattering angle of the 𝑊^± or 𝑍 boson in the parton center-of-mass frame). A multivariate variable is developed to separate the longitudinal-longitudinal polarization from other polarizations. A template fit will be performed to extract polarization fractions.