An Overview of SYCL Applications in the Context of High Energy Physics at CERN

The High-Luminosity LHC upgrade will increase the instantaneous luminosity by up to a factor of three compared to the current value, with average pile-up of around 200 interactions per bunch crossing. This will dramatically amplify the volume and complexity of data processed by the LHC experiments and therefore also the computing requirements for online and offline reconstruction. To meet this challenge, experiments are increasingly exploiting heterogeneous resources, offloading part of the simulation, reconstruction and data analysis to GPUs and other accelerators at CERN, on the WLCG, and at external HPC facilities.In this context, performance-portable programming models like SYCL are essential to keep large code bases maintainable while targeting diverse architectures and vendor ecosystems. At CERN and in the LHC collaborations, we have been evaluating SYCL as a common layer across several domains, both as a direct programming model (e.g. via Intel oneAPI/DPC++) and as an enabling technology underneath portability layers and libraries used in HEP software.This talk will present an overview of our experience with SYCL at CERN, covering use cases in reconstruction workflows for CMS and ATLAS, as well as efforts in core HEP libraries, and summarising the main challenges and lessons learned.