The Standard Model (SM) is a theory describing fundamental particles and the interaction between them. These fundamental particles are all fermions, having spin 1/2, and are grouped into three so called generations. There are six quarks, which have a charge of either -1/3 or 2/3 and six leptons, which consist of three massive leptons, the electron, the muon and the tau and their respective neutrinos. The force carriers called the gauge bosons, all have spin 1. The massless photon is the mediator of the electromagnetic force, the massless gluon is the mediator of the strong force and the massive W+/- and Z bosons are the mediators of the weak force. Latest results from ATLAS and CMS prove the existence of a Standard Model Higgs boson, a scalar boson with spin 0, which give mass to the fermions and the gauge bosons.
Study of Zyy final states
The simultaneous production of three gauge bosons of the electroweak theory is a rare process predicted by the Standard Model of particle physics with a relatively small cross section. The Run-2 dataset of the ATLAS detector offers the unique opportunity to measure and validate such processes.
Vector boson Fusion W Production
The observation and measurement of self-interactions of weak gauge bosons provide an indirect search for physics beyond the Standard Model. The electroweak production of a W boson in association with two jets includes the triple gauge boson vertices WWy and WWZ and is thus sensitive to the vector-boson-fusion (VBF) production of a W boson.
A precision measurement of the production of a W boson in assiciation with jets (W+ jets) is not only a powerful test of perturbative quantumchromodynamic (QCD) but also an important measurement for new physics searches where W+ jets events are a major background.
The signature comprising one W boson and two photons was among the first triboson final states to be detected by ATLAS. A very attractive feature of studying the Wyy final state is, that it is sensitive to the so-called quartic gauge couplings, describing a four vector boson interaction.
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