A second look at string-inspired models for proton-proton scattering via Pomeron exchange

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 a 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 parameter 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 data 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 GeV2< |t| < 0.6 GeV2, suggesting that the transition from soft Pomeron to hard Pomeron may occur closer to t = −0.5 GeV2 rather than t = −0.6 GeV2 as previously thought.