Double pomeron exchange in the reaction ifpp → pp π+π− at ISR energies

Abstract

Using the split field magnet (SFM) of the CERN ISR, we have investigated the main features of the reaction pp → pp π + π − in the kinematical region where double pomeron exchange (DPE) is supposed to play an important rôle. Using kinematically fitted events at the five standard ISR energies from √ s = 23.4 GeV to √ s = 63.4 GeV, we have studied different data subsamples as a means of distinguishing DPE from the tail of single diffraction (SD). Our results are compatible with a significant DPE contribution; in particular there is no correlation between the two protons and the s- and t-dependences follow the expected behaviour.