https://phys.org/news/2023-04-atlas-col ... -jets.html
by Ingrid Fadelli , Phys.org
The ATLAS collaboration, the large research consortium involved in analyzing data collected by the ATLAS particle collider at CERN, recently observed the electroweak production of two Z bosons and two jets. This crucial observation, presented in Nature Physics, could greatly contribute to the understanding of standard model (SM) particle physics.
The SM of particle physics is a well-established theory describing the building blocks and fundamental forces in the universe. This model describes weak bosons (i.e., bosons responsible for the so-called 'weak force') as mediators of the electroweak interaction.
The scattering of massive weak bosons, such as W and Z bosons, is constrained specifically to interactions, where the mediators themselves carry the charge of these interactions. This scattering, also known as vector-boson scattering (VBS), also involves a type of Feynman diagrams or vertices known (i.e., quartic gauge vertices) that physicists have so far been unable to experimentally probe through other physical processes.
"Quartic gauge vertices are a so far unconfirmed section of the SM, which is, however of central importance to the self-consistency of the model," Gabriela Navarro, part of the ATLAS collaboration, told Phys.org. "An example for this self-consistency is a delicate cancelation of scattering amplitudes involving Triple Gauge Vertices, Quartic Gauge Vertices and Vertices involving the Higgs Boson. A study of these processes is an independent and crucial test of the BEH-Mechanism for breaking the electroweak symmetry in the SM (EWSB)."