Changes between Version 1 and Version 2 of MadOniaDescription
 Timestamp:
 04/06/12 16:33:03 (8 years ago)
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MadOniaDescription
v1 v2 4 4 == Short description of the tool == 5 5 6 The aim is to build an event generator for quarkonium physics. Production rates are computed within the NRQCD theory (NonRelativistic QCD, Bodwin, Braaten and Lepage, see hepph/9407339), where cross sections are expanded in %$\alpha_s$% and %$\normalsize v$%, the relative velocity in the heavy quarkonium state. As a result, cross sections read6 The aim is to build an event generator for quarkonium physics. Production rates are computed within the NRQCD theory (NonRelativistic QCD, Bodwin, Braaten and Lepage, see hepph/9407339), where cross sections are expanded in $\alpha_s$ and $\normalsize v$, the relative velocity in the heavy quarkonium state. As a result, cross sections read 7 7 8 8 9 9 10 where the creation of a heavyquark pair is described by the shortdistance coefficients %$\hat \sigma(Q\bar Q(n))$%, whereas the nonperturbative evolution of this heavyquark pair into a quarkonium state is encoded into the longdistance matrix elements %$<O^{\mathcal Q}(n)>$%. The label %$\normalsize n $%stands for the intermediate state of the heavy quark pair, which is usually expressed in the spectroscopic notation:10 where the creation of a heavyquark pair is described by the shortdistance coefficients $\hat \sigma(Q\bar Q(n))$, whereas the nonperturbative evolution of this heavyquark pair into a quarkonium state is encoded into the longdistance matrix elements $<O^{\mathcal Q}(n)>$. The label $\normalsize n $ stands for the intermediate state of the heavy quark pair, which is usually expressed in the spectroscopic notation: 11 11 12 12 13 13 14 with %$\normalsize S $% the spin of the heavy quark pair, %$ \normalsize L $% its orbital angular momentum, %$ \normalsize J $% its total angular momentum, and %$ \normalsize c $%its color state.14 with $\normalsize S $ the spin of the heavy quark pair, $ \normalsize L $ its orbital angular momentum, $ \normalsize J $ its total angular momentum, and $ \normalsize c $ its color state. 15 15 16 MadOnia automatically generates any treelevel amplitude for an arbitrary transition %$\normalsize n$%(up to Pwave state) required for the computation of the shortdistance coefficients. The amplitude generator is interfaced with MadEvent to produce unweighted events. These events are written in the same format in the lhe format and can be passed through Pythia for the showering and hadronization.16 MadOnia automatically generates any treelevel amplitude for an arbitrary transition $\normalsize n$ (up to Pwave state) required for the computation of the shortdistance coefficients. The amplitude generator is interfaced with MadEvent to produce unweighted events. These events are written in the same format in the lhe format and can be passed through Pythia for the showering and hadronization. 17 17 18 18 … … 33 33 34 34 35