P _T andQ ² dependence of multijet production in γγ^* collisions

Abstract

In the context of a measurement recently performed by the PLUTO Collaboration at PETRA, we have computed the contribution of 2-jet, 3-jet and 4-jet production processes (each involving 2 large-p _T jets) in γγ^* collisions to the differential cross sectiondσ/(dp _T dQ ²), whereQ ² is the γ^*'s four momentum squared. It results that the total correction to the 2-jet contribution$\left( {\gamma \gamma ^ * \to q\bar q} \right)$, obtained forp _T andQ ² values located in the range 2 GeV<p _T <6 GeV and 0.1 GeV²<Q ²<12 GeV² varies rather slowly as a function of those two parameters; it ranges between 30% and 70%. The specific contribution of the higher twist term involving the process$\gamma \gamma ^ * \to Mq\bar q$ appears to be insignificant. The discrepancy observed between experiment and theory atQ ²≲0.3 GeV² andp _T ≃2-3.5 GeV is not explained by our results.