Hadron production in diffractive deep inelastic scattering

Abstract Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the photon dissociation system: the hadronic energy flow, the Feynman- x ( x F ) variable for charged particles, the squared transverse momentum of charged particles( p T ∗2 ), and the mean p T ∗2 as a function of x F . These distributions are compared with results in the γ ∗ p centre-of-mass frame from inclusive deep-inelastic scatteringin the fixed-target experiment EMC, and also with the predictions of several Monte Carlo calculations. The data are consistent with a picture in which the partonic structure of the diffractive exchange is dominated at low Q 2 by hard gluons.