Deep inelastic scattering at hera

Precise F-2 measurements have been performed in deep inelastic (DIS) e(+)p scattering by H1 and ZEUS over a wide range in x from 10(-5) to 0.3 and in Q(2) from 0.16 to 5000 GeV2. F-2, as well as the gluon momentum density xg(x, Q(2)), extracted from dF(2)/dlnQ(2) exhibit a fast rise as x --> 0 which shows that the proton's quark and gluon densities at small x are large. The data on F-2 as well as the first measurements of the longitudinal structure function F-L and the charm contribution to F-2, are In agreement with DGLAP evolution. Comparison of results obtained for very small values of Q(2) with theoretical models suggests that for x < 10(-2) the transition from soft to hard scattering: occurs at Q(2) values below approximate to 1 GeV2 The DIS NC and CC measurements have been extended to large values of Q(2) approximate to M-W(2), M-Z(2). For Q(2) above M-W(2) the weak force is found to have similar strength as the electromagnetic one. Combining e(+)p data from 1994-97 running: for a total integrated luminosity of 58 pb(-1) H1 and ZEUS have observed an excess of NC events over the predictions of the Standard Model (SM) for Q(2) > 15000 GeV2. The excess occurs at large x corresponding to large masses M of the e - hadron system, M around 200-230 GeV. The statistical probability that the data are compatible with the SM is at the 0.2-1% level. The data are compared with expectations for contact interactions, leptoquarks and squarks.