Hadronic cross-sections in γγ processes and the next linear Collider

Abstract

In this note we address the issue of theoretical estimates of the hadronic cross-sections for γγprocesses. We compare the predictions of the mini-jet model with data as well as other models, highlighting the band of uncertainties in the theoretical predictions, as well as those in the final values of the σ (γγ →hadrons)extracted from the data. We find that the rise of σ^tot_γγ with energy shown in the latest γγdata is in tune with the faster rise expected in the eikonal mini-jet models (EMM). We present an estimate of the accuracy with which this cross-section needs to be measured, in order to distinguish between the different theoretical models which try to "explain" the rise of total cross-sections with energy. We find that the precision of measurement required to distinguish the EMM-type models from the proton-like models, for 300 <s^½_γγ<500 GeV, is 20%, whereas to distinguish between various proton-like models or among the different parametrisations of the EMM, a precision of 8-9% or 6-7%, respectively, is required. We also comment briefly on the implications of these predictions for hadronic backgrounds at the next linear collider (NLC) to be run in the γγmode or e⁺e^-mode.