ZEUS results on the measurement and phenomenology of F2 at low x and low Q2
The ZEUS Collaboration
J. Breitweg - et al
Received: 7 September 1998 / Published online: 19 February 1999
Measurements of the proton structure function F2 for and from ZEUS 1995 shifted vertex data are presented. From ZEUS F2 data the slopes at fixed x and for x<0.01 at fixed Q2 are derived. For the latter, E665 data are also used. The transition region in Q2 is explored using the simplest non-perturbative models and NLO QCD. The data at very low Q2 are described successfully by a combination of generalised vector meson dominance and Regge theory. From a NLO QCD fit to ZEUS data the gluon density in the proton is extracted in the range .Data from NMC and BCDMS constrain the fit at large x. Assuming the NLO QCD description to be valid down to ,it is found that the sea distribution is still rising at small x and the lowest Q2 values whereas the gluon distribution is strongly suppressed.