LPC Distinguished Researcher


Alexander Grohsjean



What I will be working on:

2019 will be a particularly exciting year as it allows the LHC experiments to publish the first combined results from the full LHC Run II dataset and to probe the SM with highest precision ever. During my time at LPC, I will conclude two complementary searches for dark mattter (DM) with the full 13 TeV data set: a search for top quark associated DM production as well as a search for new scalar particles decaying into top quarks. Moreover, I intend to perform new top precision measurements, like a two-dimensional measurement of the ttbar spin density matrix. Such a measurement allows not only to better test the SM it also allows to search for new physics that involves mass scales way above LHC energies and that can be described in an effective field theory. I would like to take advantage of the current LPC research activities in the field of Higgs physics and perform first simultaneous fits to unfolded top and Higgs observables to constraint selected EFT operators taking all systematic correlations into account.

My role in CMS past and present:

I joined the CMS collaboration by the end of 2014 and I had the pleasure to perform the first measurement of the ttbar cross section at 13 TeV. Together with my research group at DESY, I am currently working on precision top quark property measurements as well as searches for dark matter. Since 2017, I am convener of the top quark properties group and I am coordinating the interpretation of top quark measurements in terms of effective field theory within CMS and the LHC Top Working Group. From 2016 onwards, I worked as convener of the Monte Carlo Validation group as well as the Matrix Element and Future Generators group. Besides the development of tools for the automized validation of new MC generator versions, I focused on pioneering state of the art MC prediction for the CMS collaboration. Another key aspect of my research is the phenomenology of particle physics with a special focus on dark matter models, effective field theory and matrix element methods. In 2016 and 2018, I was organizing the CMS Data Analysis school at DESY.