Associated transverse energy in hadronic jet production.

Abstract

We present a theoretical study of the ``pedestal height'' in hadronic jet production, i.e., the mean transverse energy per unit of rapidity 〈${\ensuremath{\omega}}_{T}^{\mathrm{ped}\mathrm{〉}}$ accompanying a high-transverse-energy jet. We find that perturbative QCD, supplemented by a Monte Carlo estimate of higher-order corrections and a soft underlying event structure similar to that of minimum-bias collisions, can account for the observed pedestal height and its dependence on jet transverse energy. We propose a way of separating the hard pedestal contribution from that of the underlying event by measuring the quantity 〈${\ensuremath{\omega}}_{T}^{\mathrm{dif}\mathrm{〉}}$, which is one-half the absolute difference of the pedestal heights on the two sides of the jet. This quantity is dominated by the hard QCD component, whereas 〈${\ensuremath{\omega}}_{T}^{\mathrm{min}\mathit{〉}=\mathit{〈}{\ensuremath{\omega}}_{T}^{\mathrm{ped}\mathrm{〉}}}$ -〈${\mathrm{\ensuremath{\omega}}}_{\mathrm{T}}^{\mathrm{dif}\mathrm{〉}}$ is dominated by the soft underlying event. We also discuss the differential distribution of pedestal height and the charged multiplicity in the pedestal.