Measurement of leading proton and neutron production in deep-inelastic scattering at HERA

Abstract.

Deep-inelastic scattering events with a leading baryon have been detected by the H1 experiment at HERA using a forward proton spectrometer and a forward neutron calorimeter. Semi-inclusive cross sections have been measured in the kinematic region $2 \le Q^2 \le 50\,{\mathrm GeV}^2$, $6\times 10^{-5}\le x\le 6\times10^{-3}$ and baryon $p_{\rm T} \le 200$ MeV, for events with a final-state proton with energy $580 \le E^{\prime} \le 740$ GeV, or a neutron with energy $E^{\prime} \ge 160$ GeV. The measurements are used to test production models and factorization hypotheses. A Regge model of leading baryon production which consists of pion, pomeron and secondary reggeon exchanges gives an acceptable description of both semi-inclusive cross sections in the region $0.7 \le E^{\prime} / E_{\rm p} \le 0.9$, where $E_{\rm p}$ is the proton beam energy. The leading neutron data are used to estimate for the first time the structure function of the pion at small Bjorken-x.