Research - Will Shepherd

My research is focused in three main directions:

Firstly, it is important to ensure that all of the data we already have in particle physics, from the state-of-the-art LHC but also from older, lower-energy measurements, is exploited fully. The data which we have already taken provides important guidelines on what is and isn't likely to be found in newer experiments. In the interest of consistency and flexibility, it is important to consider the measurements in as model-independent a way as possible. I focus my efforts in this direction on the Standard Model as an Effective Field Theory. This posits that whatever new physics there is is heavy, and uses the tools which have worked very well in understanding QCD and flavour phenomena to parameterize the effects of new physics. This framework allows agnosticism about the exact nature of the new heavy particles and nonetheless allows us to make definite statements about their potential influence on the measurements we have already made.

Second, while many specific models have been proposed to solve particular theoretical or experimental challenges to the Standard Model, we haven't yet discovered evidence for any new particles at the LHC. Given this, it becomes more important to ensure that we are collecting every scrap of information we can from the searches performed. I work to identify new phenomena which are currently neglected in the searches performed at the LHC and recommend new techniques to include these novel possibilities.

Finally, I also investigate one of the most salient experimental challenges to the Standard Model, the problem of dark matter. It is well known that there is additional mass in the universe which is not made up of ordinary matter and which is crucial to the formation of galaxies and clusters as we observe them. This source of additional mass is totally unknown. There are multiple models in particle physics which predict, that particles which interact rarely (but more strongly than through gravity) with ordinary matter can naturally have an abundance in the universe which comports with our measurements. I have worked to ensure that all experiments which have data potentially sensitive to the properties of dark matter explore exactly what they have to say about it, and continue to serve as a member of the LHC Dark Matter Working Group, setting priorities for the LHC experiments and advising them on how best to report their results so that they can be fairly compared with other dark matter experiments.