Measurement of the jet width in γγ collisions and in e+e− annihilation process at TRISTAN

The shape of jets produced in (quasi-) real photon-photon collisions as well as in e+e− annihilation process has been studied with a cone jet finding algorithm, using the data taken with the TOPAZ detector at the TRISTAN e+e− collider at an average center-of-mass energy (see) of 58 GeV. The results are presented in terms of the jet width as a function of the jet transverse energy (ETjet) as well as a scaled transverse jet energy, xT (=2ETjet/s). The jet width narrows as EjetT increases; however, at the same value of ETjet the jet width in γγ collisions at TRISTAN is significantly narrower than that in γp collisions at HERA. By comparing our results with the data in other reactions, it has been shown that the jet width in γγ, γp, pp̄ collisions as well as the e+e− annihilation process has an approximate scaling behavior as a function of xT.