I am a 4th year PhD student working within the ATLAS group here at Warwick. I was based at CERN for my 2nd and 3rd year and was lucky enough to get the opportunity to work on-site for some of it. My main area of interest is in the Higgs sector of the Standard Model. Having been discovered in 2012, the Higgs boson was the last piece of the Standard Model to be confirmed and as such, there is still a lot more to understand about it. The Higgs boson could also play a role in discovering physics beyond the Standard Model, which we know is necessary in order to fully describe the universe and find the solutions to many open questions. I think it is a very exciting and progressive field of research to be involved in.
Currently, I am involved in an analysis searching for the decay of a boosted Higgs boson to a bottom quark-antiquark pair, recoiling against another jet. This decay is the most common of the Higgs boson decays, with a branching fraction of 58%; however, there are a significant number of background processes with similar kinematic properties, making it very difficult to distinguish the signal from background. An initial result has been presented in a conference note and we are now working to improve this analysis for the next iteration by optimising various aspects of the analysis.
One factor that is of particular interest to optimise is b-tagging. At the LHC, the proton-proton collisions produce many different interactions, a lot of which result in jets that need to be differentiated from one another. Flavour tagging can be employed in order to distinguish the flavour of these jets and I have been working on the calibration of a new Xbb tagger, which aims to identify boosted resonances that decay to a b-quark pair, similar to the signature of the analysis above. Monte Carlo generators are used to simulate events and responses of the detectors at the LHC and therefore, it is important to have comparisons between the simulations and the actual data. My work used the Z boson mass resonance in events to provide calibration scale-factors for this tagger. The public note was released in August 2021.