A Second Look at String-Inspired Models for Proton-Proton Scattering via Pomeron Exchange

TL;DR

This paper re-examines string-inspired models for proton-proton scattering via Pomeron exchange, exploring generalized Reggeization methods and their fit to experimental data, revealing potential improvements and discrepancies in the model parameters.

Contribution

It introduces a generalized Reggeization approach with a variable mass-shell parameter and analyzes its impact on fitting scattering data, offering insights into the soft-hard Pomeron transition.

Findings

Generalized Reggeization can improve data fit with variable mass-shell.

Traditional Reggeization yields more physically consistent parameters.

Model aligns better with E710 data than CDF, and suggests transition near t = -0.5 GeV^2.

Abstract

We re-examine a string dual model for elastic proton-proton scattering via Pomeron exchange. We argue that the method of "Reggeizing" a propagator to take into account an entire trajectory of exchanged particles can be generalized, in particular by modifying the value of the mass-shell parameter in the model. We then fit the generalized model to scattering data at large s and small t. The fitting results are inconclusive, but suggest that a better fit might be obtained by allowing the mass-shell to vary. The model fits the data equally well (roughly) for a wide range of values of the mass-shell parameter, but the other fitting parameters (the slope and intercept of the Regge trajectory, and the coupling constant and dipole mass from the proton-proton-glueball coupling) are then inconsistent with what we expect. On the other hand, using the traditional method of Reggeization generates a weaker fit, but the other parameters obtain more physically reasonable values. In analyzing the fitting results, we also found that our model is more consistent with the sqrt(s) = 1800 GeV coming from the E710 experiment than that coming from the CDF experiment, and that our model has the greatest discrepancy with the data in the range 0.5 GeV^2 < |t| < 0.6 GeV^2, suggesting that the transition from soft Pomeron to hard Pomeron may occur closer to t = -0.5 GeV^2 rather than t = -0.6 GeV^2 as previously thought.