Hadron induced lepton production

In recent years the study of hadronic production of leptons has occupied a prominent place in high-energy physics, with a number of very important results to its credit. These are widely reviewed in the literature and discussed here. Relatively more emphasis is, however, given to some very recent results, which have emerged from work carried out at the CERN Intersecting Storage Rings (ISR), where a broad programme of lepton studies was initiated a few years ago. (58 refs).