DOI 10.1007/s100529901084
ZEUS results on the measurement and phenomenology of F2 at low x and low Q2
The ZEUS Collaboration
J. Breitweg - et al
Argonne National Laboratory, Argonne, IL, USA
Received: 7 September 1998 / Published online: 19 February 1999
Abstract
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.
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