Target fragmentation in $pp$, $ep$ and $\gamma p$ collisions at high energies

U. D'Alesio; H.J. Pirner

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2023 Impact factor 2.6

Hadrons and Nuclei

Eur. Phys. J. A 7, 109-119

Target fragmentation in pp, ep and $\gamma p$ collisions at high energies

U. D'Alesio - H.J. Pirner

Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 19, 69120 Heidelberg, Germany

Received: 12 June 1999 / Revised version: 12 October 1999 Communicated by F. Lenz

Abstract
We calculate target fragmentation in $p p \rightarrow n X$ and $\gamma p \rightarrow n X$ reactions in the meson cloud picture of the nucleon. The $p p \rightarrow n X$ reaction is used to fix the $pn\pi^+$ form factor for three different models. We take into account the possible destruction of the residual neutron by the projectile. Using the form factor from the hadronic reaction we calculate photoproduction and small $x_{\rm Bj}$ electroproduction of forward neutrons at HERA. Here the $q \bar q$ dipoles in the photon can rescatter on the residual neutron. In photoproduction we observe slightly less absorption than in the hadronic reaction. For deep inelastic events (Q²>10 GeV²) screening is weaker but still present at large Q². The signature for this absorptive rescattering is a shift of the $d\sigma/dE_n$ distribution to higher neutron energies for photofragmentation.