Changes between Initial Version and Version 1 of FAQ-General-13


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Timestamp:
05/15/12 12:13:00 (8 years ago)
Author:
JohanAlwall
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  • FAQ-General-13

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     3=== What are the default dynamic factorization and renormalization scales in !MadEvent? ===
     4
     5Since v.4.2.17, there is a new default dynamical scale choice in run_card.dat file:
     6
     7{{{
     8#*********************************************************************
     9# Renormalization and factorization scales                           *
     10#*********************************************************************
     11 F        = fixed_ren_scale  ! if .true. use fixed ren scale
     12 F        = fixed_fac_scale  ! if .true. use fixed fac scale
     13 91.1880  = scale            ! fixed ren scale
     14 91.1880  = dsqrt_q2fact1    ! fixed fact scale for pdf1
     15 91.1880  = dsqrt_q2fact2    ! fixed fact scale for pdf2
     16 1        = scalefact        ! scale factor for event-by-event scales
     17}}}
     18
     19
     20i.e., variable factorization and renormalization scales,set to the central mT^2 scale after kT-clustering of the event.
     21For a single heavy particle, this corresponds to the M^2+pT^2,
     22for pair of heavy particles it is the geometric mean of M^2+pT^2 for each particle,
     23for massless particles it is the pT^2 of the last pair after clustering.
     24If the last clustering is a t-channel colorless exchange (as, e.g., in WBF),  the two fact. scales are set to the last mT^2 values on either side.
     25These scales are overridden by scales defined in [http://bazaar.launchpad.net/~madteam/madgraph5/trunk/view/head:/Template/SubProcesses/setscales.f setscales.f], if they are returned as non-0.
     26
     27See [wiki:FAQ-General-2 How do I implement my own renormalization/factorization scales in MadEvent ?] for information about how to implement your own scales in MadEvent.