  We introduce HepLean, an open-source project to digitalise definitions,
theorems, proofs, and calculations in high energy physics using the interactive
theorem prover Lean 4. HepLean has the potential to benefit the high energy
physics community in four ways: making it easier to find existing results,
allowing the creation of new results using artificial intelligence and
automated methods, allowing easy review of papers for mathematical correctness,
and providing new ways to teach high energy physics. We will discuss these in
detail. We will also demonstrate the digitalisation of three areas of high
energy physics in HepLean: Cabibbo-Kobayashi-Maskawa matrices in flavour
physics, local anomaly cancellation, and Higgs physics.
