Soft processes at the LHC, I: Multi-component model

TL;DR

Soft hadronic interactions at high energy are strongly influenced by absorptive multi-Pomeron effects, requiring a multi-component eikonal framework with diffusion in impact parameter $b$ and in $\ln k_t$. The authors develop a 3-channel $s$-channel and 4-state $t$-channel model, incorporating low-mass diffractive dissociation (Good-Walker) and enhanced high-mass contributions via a complete set of multi-Pomeron vertices, and solve coupled evolution equations for opacities. Fitting CERN-ISR to Tevatron data, the model makes LHC predictions including $\\sigma_{tot} \sim 90$ mb, sizeable diffractive cross sections, and central exclusive production with gap survival effects, highlighting a slow growth of the total cross section and differential observables via absorptive corrections. The framework links soft Regge phenomenology to the soft–hard Pomeron transition, providing insights into rapidity-gap survival and underlying-event structure relevant for LHC phenomenology.

Abstract

We emphasize the sizeable effects of absorption on high-energy `soft' processes, and, hence, the necessity to include multi-Pomeron-Pomeron interactions in the usual multi-channel eikonal description. We present a model which includes a complete set of the multi-Pomeron vertices and which accounts for the diffusion in both, the impact parameter and ln(k_t), of the parton during its evolution in rapidity. We tune the model to the available data for soft processes in the CERN-ISR to Tevatron energy range. We make predictions for `soft' observables at the LHC.

Figures (13)

• Figure 1: The eikonal model of elastic scattering
• Figure 2: A multi-Pomeron vertex
• Figure 3: The evolution of the elastic bare Pomeron amplitude, $\Omega_k(y,b)$.
• Figure 4: A pure inelastic high multiplicity process
• Figure 5: The ladder structure of the triple-Pomeron amplitude.