NEW CLUSTERING-ALGORITHM FOR MULTIJET CROSS-SECTIONS IN E+E- ANNIHILATION

Cross sections for e+e- --> n-jets, as functions of the jet resolution parameter y(cut), are computed according to a new clustering algorithm. The jet multiplicity n is defined in such a way that jets i and j with energies E(i) and E(j) at relative angle theta-ij are resolved if y(ij) = 2(1-cos theta-ij) min (E(i)2, E(j)2)/s > y(cut), where s is the centre-of-mass energy squared. Using this algorithm, large higher-order corrections at small values of y(cut) can easily be evaluated. Our calculations include resummation of leading and next-to-leading logarithms of y(cut) to all orders in QCD perturbation theory. This enables us to predict the jet cross sections at small y(cut) for arbitrary n. Simple analytical results for n less-than-or-equal-to 5 are presented.