A Problem in Virtual Graviton exchanges in Flat Large Extra Dimensions

TL;DR

This paper highlights a significant issue in models with large extra dimensions where virtual graviton exchange cross sections can be vastly misestimated due to lack of momentum conservation in extra dimensions, affecting collider experiment interpretations.

Contribution

It identifies and explains a problem in calculating virtual graviton exchange cross sections in large extra dimension models, emphasizing the need for careful interpretation in collider searches.

Findings

Virtual graviton exchange cross sections can be vastly over- or under-estimated.

The problem stems from the lack of momentum conservation in extra dimensions.

Previous results on cross sections may need revision for accurate collider predictions.

Abstract

It is pointed out in a class of models with large extra dimensions that the cross section of processes with virtual Kaluza-Klein graviton exchanges becomes either much smaller or much larger by many orders of magnitude than what is expected from that of the on-shell production of the Kaluza-Klein gravitons. We demonstrate how the problem arises using a toy model. The cause of this new problem lies in the fact that we do not have momentum conservation in the extra dimensions. To search for the signal of the large extra dimensions with high energy collider experiments, we need more care in interpreting the earlier results on the cross sections of these processes.