Studying Electroweak Gauge-Boson Self-Interactions in Final States including a Z and a Photon

This student project studies double and triple electroweak gauge boson (W,Z,photon) production in proton-proton collision data collected with the ATLAS detector. The work builds on previous measurements of Z+photon production using ATLAS data collected in 2015-2018, and will look both at processes where the Z+photon is produced by collision of electroweak bosons emitted off the constituents of the incoming protons ("vector-boson scattering") as well as production of three vector bosons including Z, photon and another electroweak gauge boson. These measurements should provide first observations of some of these processes with ATLAS, and will in any case probe for possible higher-than-Standard Model production rates, constraining beyond-the-Standard Model effects. Furthermore more detailed studies of the Z+photon final-state will be made, compared to those done previously.

In addition, studies are being made of the performance of the second round ("Phase-II") trigger upgrade of ATLAS, specifically with regard to electron and photon triggering at the very first level ("Level-0") - detailed implementation of improved algorithms for these triggers must be established in the coming years, and the project will deliver this.
It is further anticipated that the project will include some operational responsibility for the trigger system when LHC data-taking restarts in 2021.

The project analyses experimental data from the 2015-2018 data-taking run of the CERN Large Hadron Collider (LHC), and will also include a first look at the next data, which is expected to arrive from 2021 - especially if the LHC collision energy is increased then.

The bulk of all the work described will be done by the student, with appropriate supervision, and in close collaboration with colleagues in Birmingham, and from other institutes which are members of the ATLAS Collaboration.