Central diffraction in proton-proton collisions at √(s) = 7TeV with ALICE at LHC

A double-gap topology is used for filtering central-diffractive events from a protonproton minimum-bias data sample at a centre-of-mass energy Central diffraction in proton-proton collisions at √(s) = 7TeV. This topology is defined by particle activity in the ALICE central barrel and absence of particle activity outside. The fraction of events satisfying the double-gap requirement RDG is found to be 7.63±0.02(st at.)±0.87(syst.)×10−4. The background of this double-gap fraction is estimated by studying the contributions of non-diffractive, single-and double-diffractive dissociation processes as modelled by Monte Carlo event generators, and is found to be about 10%.