On the model-dependence of the relation between minimum-bias and inelastic proton-proton cross sections

The model-dependence of the relation between the inelastic and various minimum-bias proton-proton cross sections is analyzed, paying a special attention to the sensitivity of minimum-bias triggers to diffractive collisions. Concentrating on the trigger selections of the ATLAS experiment, the measured cross sections are compared to predictions of a number of hadronic Monte Carlo models used in the cosmic ray field. It is demonstrated that the ATLAS results are able to discriminate between different models and between certain theoretical approaches for soft multi-particle production. On the other hand, the strong model-dependence of the selection efficiency of the minimum-bias triggers prevents one from inferring high mass diffraction rate from the discussed data. Moreover, the measured cross sections prove to be insensitive to the production of low mass diffractive states in proton-proton collisions. Consequently, a reliable determination of the total inelastic cross section requires forward proton tracking by a dedicated experiment.Comment: PLB versio

Rapidity Gap Survival in Enhanced Pomeron Scheme

We apply the phenomenological Reggeon field theory framework to investigate rapidity gap survival (RGS) probability for diffractive dijet production in proton-proton collisions. In particular, we study in some detail rapidity gap suppression due to elastic rescatterings of intermediate partons in the underlying parton cascades, described by enhanced (Pomeron-Pomeron interaction) diagrams. We demonstrate that such contributions play a subdominant role, compared to the usual, so-called "eikonal", rapidity gap suppression due to elastic rescatterings of constituent partons of the colliding protons. On the other hand, the overall RGS factor proves to be sensitive to color fluctuations in the proton. Hence, experimental data on diffractive dijet production can be used to constrain the respective model approaches

Hadronic Interactions at Cosmic Ray Energies

General physics of very high energy hadronic interactions is discussed. Special attention is payed to the contribution of semihard processes to the interaction dynamics and to the role of parton shadowing and parton density saturation. In particular, the implementation of non-linear interaction effects in the QGSJET-II model is discussed in detail. The predictions of the model are compared to selected accelerator data, including ones of the RHIC collider, and the relation to the calculated extensive air shower characteristics is discussed. Finally, the potential of accelerator and cosmic ray experiments for constraining model predictions is analyzed.Comment: Prepared for the 14th International Symposium on Very High Energy Cosmic Ray Interactions, August 15-22, 2006, Weihai, Chin