Charis Kleio Koraka

The CMS experiment at CERN accelerates several stages of its online reconstruction by making use of GPU resources at its High Level Trigger (HLT) farm for LHC Run 3. Additionally, during the past years, computing resources available to the experiment for performing offline reconstruction, such as Tier-1 and Tier-2 sites, have also started to integrate accelerators into their systems. In order to make efficient use of these heterogeneous platforms, it is essential to adapt both the CMS production system and the CMSSW reconstruction code to make use of GPUs. The CMSSW offline reconstruction can now partially run on GPUs, inheriting from the work done at the HLT. Parts of the production systems infrastructure have also been adapted to successfully map, schedule and run the available GPU-enabled workflows on different sites across the computing grid. This talk will describe the process of commissioning GPU-enabled CMSSW workflows through the production system and will present first results from the deployment of GPU-enabled offline reconstruction workflows.

The search for the associated production of a Higgs boson with a top quark–antiquark pair with the CMS detector will be presented. Candidate $$t\bar{t}H$$ events are selected with criteria enhancing respectively the dileptonic, semileptonic and fully hadronic decay channels of the $$t\bar{t}$$ system and the decay of the Higgs boson into a bottom quark–antiquark pair ( $$H\rightarrow b\bar{b}$$ ). In order to increase the sensitivity of the search, selected events are split into several categories with different expected signal and background rates. A combined fit of multivariate discriminant templates across all categories and decay channels is performed to extract the result. Results for Run II data will be shown. Prospects for improvements towards Run III will also be discussed.