Speaker
Emmanuel Sauvan
(LAPP (IN2P3/CNRS))
Description
Measurements of the cross section for the diffractive process ep -> eXY are presented,
where Y is a proton or a low mass proton excitation carrying a fraction 1 − xIP > 0.95
of the incident proton longitudinal momentum and the squared four-momentum transfer
at the proton vertex satisfying MY < 1.6 GeV and |t| < 1.0 GeV^2. Using data taken
by the H1 experiment, the cross section is measured for photon virtualities in the range
3 <= Q2 < =1600 GeV^2, triple differentially in xIP , Q^2 and beta = x/xIP , where x is the
Bjorken scaling variable. Thesemeasurements are made after selecting diffractive events by
demanding that a large rapidity interval separates the final state hadronic systems X and Y .
New measurements covering data taking periods 1999-2000 and 2004-2007 are combined
with previously published results in order to provide a single set of diffractive cross sections
using the large rapidity gap selection method from the H1 experiment. Comparisons of
measurements with predictions from the diffractive parton density and dipole models are
shown. Finally, the proton vertex factorisation hypothesis, which is an important aspect in
the modelling of diffractive structure, is discussed.
Author
Richard Polifka
(University of Toronto (CA))
