Changes between Version 1 and Version 2 of IntroQuarkonium


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Timestamp:
04/06/12 16:33:02 (8 years ago)
Author:
trac
Comment:

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  • IntroQuarkonium

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    33=== Short description of the tool ===
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    5 The aim is to build an event generator for quarkonium physics. Production rates are computed within the NRQCD theory (Non-Relativistic QCD, Bodwin, Braaten and Lepage, see hep-ph/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
     5The aim is to build an event generator for quarkonium physics. Production rates are computed within the NRQCD theory (Non-Relativistic QCD, Bodwin, Braaten and Lepage, see hep-ph/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
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    9 where  the creation of a heavy-quark pair is described by the short-distance coefficients %$\hat \sigma(Q\bar Q(n))$%, whereas the non-perturbative evolution of this heavy-quark pair into a quarkonium state is encoded into the long-distance 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:
     9where  the creation of a heavy-quark pair is described by the short-distance coefficients $\hat \sigma(Q\bar Q(n))$, whereas the non-perturbative evolution of this heavy-quark pair into a quarkonium state is encoded into the long-distance 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:
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    13 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.
     13with $\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.
    1414 
    15 MadOnia automatically generates any tree-level amplitude for an arbitrary transition %$\normalsize n$% (up to P-wave state) required for the computation of the short-distance 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.
     15MadOnia automatically generates any tree-level amplitude for an arbitrary transition $\normalsize n$ (up to P-wave state) required for the computation of the short-distance 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.
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    2626}}}
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    28 This corresponds to the production of a %$\normalsize J/\psi$% (PID=443) via an intermediate state %$\normalsize 2S+1=3$%, %$\normalsize L=P$%, %$\normalsize J=1$%, %$\normalsize c=8$%, i.e. a spin-1,  P-wave, color-octet intermediate state. As another example:
     28This corresponds to the production of a $\normalsize J/\psi$ (PID=443) via an intermediate state $\normalsize 2S+1=3$, $\normalsize L=P$, $\normalsize J=1$, $\normalsize c=8$, i.e. a spin-1,  P-wave, color-octet intermediate state. As another example:
    2929
    3030{{{
     
    3232}}}
    3333
    34 corresponds to the production of an %$\normalsize \eta_b$% via a color-singlet transition.
     34corresponds to the production of an $\normalsize \eta_b$ via a color-singlet transition.
    3535
    3636'''Pay attention'''
     
    6363have a block called LDME. The parameters in this block
    6464correspond to the long distance matrix element, expressed in the BBL normalization (see hep-ph/9407339).
    65 You can specify the value of the LDME's for each transition. The transition %$\normalsize n$% is indicated at the end of the line
     65You can specify the value of the LDME's for each transition. The transition $\normalsize n$ is indicated at the end of the line
    6666as a comment. For example, the line
    6767
     
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    76 Note that only one LDME parameter is assigned to each transition %$^{2S+1}L_J^{[c]}$%. For example, for all the  following processes
     76Note that only one LDME parameter is assigned to each transition $^{2S+1}L_J^{[c]}$. For example, for all the  following processes
    7777
    78    || pp >j cc~[3S18to443]    ||               color-octet  %$\normalsize J/\psi$% production ||
    79    || pp > jcc~[3S18to10441]  ||             color-octet  %$\normalsize \chi_{c0}$% production ||
    80    || pp > jbb~[3S18to100553]    ||       color-octet  %$\normalsize \Upsilon(2S)$% production ||
     78   || pp >j cc~[3S18to443]    ||               color-octet  $\normalsize J/\psi$ production ||
     79   || pp > jcc~[3S18to10441]  ||             color-octet  $\normalsize \chi_{c0}$ production ||
     80   || pp > jbb~[3S18to100553]    ||       color-octet  $\normalsize \Upsilon(2S)$ production ||
    8181
    8282the same LDME parameter will be used in the param_card.dat.
     
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