Hadronic Cross-Sections in γγ Processes and the Next Linear Collider

In this note we address the issue of theoretical estimates of the hadronic cross-sections for γγ processes. We compare the predictions of the minijet model with data and with other models, highlighting the band of uncertainties in σ(γγ→hadrons) extracted from the data.We find that the rise of σ_γγ^tot with energy shown in the latest γγ data is in tune with the faster rise expected in the Eikonal Minijet Models (EMM).We present an estimate of the accuracy with which this cross-section needs to be measured 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 ≲20%, whereas to distinguish between various proton-like models or between different parametrizations of the EMM, a precision ≲8-9% or ≲ 6-9% respectively, for 300<√(s_γγ )<500 GeV. We also comment briefly on the implications for the predictions for the hadronic backgrounds at the next linear collider (NLC) to be run in the γγ mode e^+ e^- mode.