Measurement of diffractive scattering of photons with large momentum transfer at HERA

The first measurement of diffractive scattering of quasi-real photons with large momentum transfer γp→γYγp→γY, where Y   is the proton dissociative system, is made using the H1 detector at HERA. The measurement is performed for initial photon virtualities Q2<0.01 GeV2Q2<0.01 GeV2. Single differential cross sections are measured as a function of W, the incident photon–proton centre of mass energy, and t  , the square of the four-momentum transferred at the proton vertex, in the range 175