1,721,196 research outputs found
A Positive-weight next-to-leading-order Monte Carlo for Z pair hadroproduction
No full textWe present a first application of a previously published method for the computation of QCD processes that is accurate at next-to-leading order, and that can be interfaced consistently to standard shower Monte Carlo programs. We have considered Z pair production in hadron-hadron collisions, a process whose complexity is sufficient to test the general applicability of the method. We have interfaced our result to the HERWIG and PYTHIA shower Monte Carlo programs. Previous work on next-to-leading order corrections in a shower Monte Carlo (the MC@NLO program) may involve the generation of events with negative weights, that are avoided with the present method. We have compared our results with those obtained with MC@NLO, and found remarkable consistency. Our method can also be used as a standalone, alternative implementation of QCD corrections, with the advantage of positivity, improved convergence, and next-to-leading logarithmic accuracy in the region of small transverse momentum of the radiated parton
A Positive-weight next-to-leading-order Monte Carlo for heavy flavour hadroproduction.
No full textWe present a next-to-leading order calculation of heavy flavour production in hadronic collisions that can be interfaced to shower Monte Carlo programs. The calculation
is performed in the context of the POWHEG method [1]. It is suitable for the computation of charm, bottom and top hadroproduction. In the case of top production, spin correlations in the decay products are taken into account
A Study of ultraviolet renormalon ambiguities in the determination of alpha-s from tau decay
No full text
Instanton effects in the light-quark masses determination from QCD sum rules
No full textWe consider the determination of the light-quark masses obtained from QCD sum rules. We show that small-size instantons contribute sizeable corrections to these sum rules. It therefore seems impossible to provide an accurate determination of the light-quark masses in the QCD sum rules framework
- …
