Elastic proton-proton scattering at LHC energies in holographic QCD

Wei Xie,Akira Watanabe,Mei Huang

doi:10.1007/jhep10(2019)053

Abstract

The cross sections of the high energy proton-proton scattering are studied in a holographic QCD model, focusing on the Regge regime. In our model setup, the involved nonperturbative partonic dynamics is described by the Pomeron exchange, which is realized by applying the Reggeized spin-2 particle propagator together with the proton gravitational form factor obtained from the bottom-up AdS/QCD model. Our model includes three adjustable parameters which are to be fitted by experimental data. We show that both the resulting differential and total cross sections are consistent with data, including the ones recently measured at sqrt{s} = 13 TeV by the TOTEM collaboration at the LHC. Our results imply that the present framework works well in the considered TeV scale, and further applications to other high energy scattering processes, in which the involved strong interaction can be approximated by the Pomeron exchange, are possible.

Highlights

The cross sections of the high energy proton-proton scattering are studied in a holographic QCD model, focusing on the Regge regime
The involved nonperturbative partonic dynamics is described by the Pomeron exchange, which is realized by applying the Reggeized spin-2 particle propagator together with the proton gravitational form factor obtained from the bottom-up AdS/QCD model
Our results imply that the present framework works well in the considered TeV scale, and further applications to other high energy scattering processes, in which the involved strong interaction can be approximated by the Pomeron exchange, are possible

Summary

Holographic description of proton-proton scattering in the Regge regime

The formalism which describes the pp scattering in the Regge regime with the Pomeron exchange has been developed in ref. [55]. The scattering amplitude is obtained by combining the Pomeron propagator and the gravitational form factor of the proton. In order to calculate the gravitational form factors, we consider the gravity-dilaton-tachyon action [67, 68], and in which the metric of the AdS space is perturbed from its static solution according to ημν → ημν + hμν. The Q2 dependencies of the proton gravitational form factors obtained from both the hardwall and the soft-wall models are shown in figure 2. These results are comparable with that calculated from a GPD model [69], while the soft-wall model result is more consistent with the GPD result compared to the hard-wall one

Kinematic regions and model parameters

Fitting results

Findings

Summary and discussion