HERA Groups Find Excess Deep Inelastic ${\mathrm{e}}^{+}\mathrm{p}$ Scattering Events

Over the last four years, the H1 and ZEUS detector groups at DESY in Hamburg have been studying the interaction of 27.5 GeV positrons colliding with 820 GeV protons in the Hadron‐Electron Ring Accelerator (HERA). The events at the highest 4‐momentum transfer explore a new kinematic regime, down to ${10}^{\text{−16}}\hspace{0.17em}\mathrm{cm}.$ As early as 1994, some deep inelastic scattering events at very high momentum transfer were seen. Late last year, rumors became rampant in labs outside DESY that the H1 and ZEUS detectors were finding leptoquarks. Both groups independently analyzed their data sample of high‐energy deep inelastic scattering collected from 1994 to 1996. The events they found have the signature of deep inelastic scattering—tne positron is scattered by a quark inside the proton through a large angle, almost completely back the way it came, and the struck quark generates a high‐energy jet of hadrons.