LIV.DAT student Ricardo Gonzalez Lopez passes PhD viva

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LIV.DAT student Ricardo Gonzalez Lopez has successfully defended his PhD thesis titled ‘New heavy gauge boson searches at ATLAS and their phenomenological interpretation’.

The neutral-current Drell-Yan production is a process for which precise predictions are currently available, offering a benchmark upon which these state-of-the-art predictions can be tested, both as a way to improve our understanding of Standard Model physics and explore theories that expand on the foundations it establishes. Ricardo’s thesis provides an overview of two analyses focusing on the Drell-Yan production using LHC Run 2 proton-proton collision data collected by the ATLAS experiment during the years 2015 to 2018.

First, Ricardo worked on a measurement of the single and double-differential production cross-section in an invariant mass region of 116 to 5000 GeV, using Z/γ* decays into lepton pairs in the electron and muon channels. The results obtained were used to perform for the first time tests on lepton flavour universality (LFU) as well as set limits on Effective Field Theory (EFT) coefficients that modify the Drell-Yan production cross-section.

Ricardo also worked on a novel search for Lorentz-invariance violating (LIV) signatures using Z-decays into electron and muon pairs. Using the methodology for a luminosity measurement based on the counting of Z-bosons detected, the time-dependence of the Drell-Yan production can be monitored. While the Standard Model predicts no time-dependence on this process, deviations from this behaviour can be interpreted as the effects of LIV-inducing operators in the Standard Model Extension EFT.

Ricardo said ‘I really enjoyed my PhD experience as a whole. To be able to work for a great collaboration such as ATLAS, and surrounded by so many amazing people has been an incredible opportunity.’

‘I also enjoyed being part of the LIV.DAT CDT. Not only it brought me closer to some of my colleagues, but it also allowed to expand the training I received during my PhD, even put some of those new skills in practice with my industry placement.’

Since submitting his thesis, Ricardo has been working as a Software Implementation Analyst at Alfred H Knight, where he can put in practice both the technical and soft skills he acquired during my PhD.

Congratulations Ricardo!