Giuseppe Marchesini

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HERWIG is a general-purpose Monte Carlo event generator, which includes the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron scattering and soft hadron-hadron collisions in one package. It uses the parton-shower approach for initialand final-state QCD radiation, including colour coherence effects and azimuthal correlations both within and(More)
We perform the two-loop analysis of the 1/Q power corrections to jet-shape variables. This step is necessary for producing reliable theoretical predictions for the relative magnitudes of genuine confinement effects. We show that the rescaling factor recently derived for the thrust case (the Milan factor) remains the same for the class of observables which(More)
We consider interjet observables in hard QCD processes given by the energy flow Eout in a region away from all hard jets. Here the QCD radiation is depleted (Eout ≪ Q), and therefore these observables provide ideal means to study non-perturbative effects. We derive an evolution equation (in the large Nc limit) which resums, for large Q/Eout, all leading(More)
The perturbative all-order analysis of the jet-broadening B-distribution in the small-B region is carried out with single-logarithmic accuracy, which requires the control of both the sum of the moduli and the modulus of the sum of the transverse momenta of soft gluons. We confirm the master equation for the B-distribution derived by Catani, Turnock and(More)
We address the problem of potential non-universality of the leading 1/Q power corrections to jet shapes emerging from the non-inclusive character of these observables. We consider the thrust distribution as an example and analyse the non-inclusive contributions which emerge at the two-loop level. Although formally subleading in αs, they modify the existing(More)
Abstract: A general discussion is presented of the single logarithmic soft factor that appears in two scale QCD observables in processes involving four partons. We treat it as the “fifth form factor”, accompanying the four collinear singular Sudakov form factors attached to colliding and outgoing hard partons. The fifth form factor is expressed in terms of(More)
We calculate ee → QQ̄(k)+ anything in a certain momentum, k, region for heavy quark-antiquark (QQ̄) production. In our chosen region we find that the number of heavy quark pairs produced is determined by BFKL dynamics and the energy dependence of the number of pairs is given by αP−1 the hard pomeron intercept.
We recall the origin of angular ordering of soft parton emission in the region of small x and show that this coherent structure can be detected in associated distributions. For structure functions at small x and at fixed transverse momentum the angular ordering is masked because of the complete inclusive cancellations of collinear singularities for x → 0.(More)