Observation of events at very high Q**2 in E P Collisions at HERA

Measurements of ep scattering with squared 4—momentum transfer Q2 up to 35000 GeV2 are compared with the expectation of the standard deep-inelastic model of lepton—nucleon scattering (DIS). For Q2 > 15000 GeV2, N obs = 12 neutral currentcandidate events are observed where the expectation is N DIS = 4.71 ± 0.76 events. In the same Q2 range, N obs = 4 charged currentcandidates are observed where the expectation is N DIS = 1.77 ± 0.87 events. The probability P(N ≥ N obs) that the DIS model signal N fluctuates to N ≥ N obs in a random set of experiments is 6 × 10−3 for neutral currentand 0.14 for charged current. The difference in the observed and expected number of Neutral Currentevents is mostly due to events at large masses \(M = \sqrt {xs}\) in which the positron is backscattered at large y = Q2/M2.