Double-tag events study with the L3 detector at sqrt(s)=189 GeV

TL;DR

This study measures gamma* gamma* collision cross-sections at 189 GeV using the L3 detector, confirming perturbative QCD predictions and highlighting limitations of the Quark Parton Model.

Contribution

First measurement of gamma* gamma* cross-sections at this energy, comparing data with perturbative QCD and BFKL calculations.

Findings

Results agree with perturbative QCD predictions.

Quark Parton Model alone is insufficient.

Data lies between LO and NLO BFKL calculations.

Abstract

A preliminary study of double tag events using the L3 detector at center of mass energy sqrt{s}=189 GeV has been performed. The cross-section of gamma* gamma* collisions is measured at average <Q2>=14.5 GeV2. The results are in agreement with predictions based on perturbative QCD, while the Quark Parton Model alone is insufficient to describe the data. The measurements lie below the LO and above the NLO BFKL calculations.