LPSC EVENT GENERATORS : MC@NLO using HERWIG

LPSC Generator Page : MC@NLO using HERWIG

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MC@NLO Documentation

MC@NLO Manual :

MC@NLO 3.2 is compatible with HERWIG 6.5 or higher.

MC@NLO Home page : MC@NLO Site

Last Release : "The MC@NLO 3.3 Generator" (pdf) [2006]

Old release : "The MC@NLO 3.2 Generator" (pdf) [FEB-2004]

Related Documents:

Herwig Manual : HERWIG 6.5 (ps)

PDFLIB manual : PDFLIB 8.04 (ps)

Example http://www.nikhef.nl/pub/experiments/atlaswiki/index.php/MCatNLO_howtoof event generation

For a complete "how to generate events" guide, see Guide@NIKHEF or below

Input Processes :

Single top : IC = 10 (s-channel) , 20 (t-channel)

Event Generation by example (Adapted from NIKHEF page)

CROSS-SECTION INTEGRATION
The integration computes the cross-sections and produces the BASE files (or *.data files*). Those files contain all the information (phase space, etc...) needed to generate the events at the parton level.

Set the parameters for the integration

Go to the Run directory
>cd MC@NLO32/

Set the input parameters in the integration input file :
> edit MCatNLO_tch.inputs.Integration.
Main user parameters are:

------------------------------------------------------------------------------------------------------------------
         IPROC  -2020    ! t-channel production (t and tbar) 
         ...
         PDFGROUP=CTEQ   ! Set the PDF name and set 
         PDFSET= 56      ! to ...CTEQ6M
         ...
         FPREFIX=TCH     ! PREFIX for BASES files 
         EVPREFIX=TCH    ! PREFIX for event files
         EXEPREFIX=TCH   | PREFIX for executable
         ...     
         HWPATH="/xxx/atlas/l/lucotte/3.MC@NLO/HERWIG" ! path to the Herwig directory
         HERWIGVER="herwig6506.o"   ! Herwig version 
         SCRTCH=""       ! store data and event files in the running directory
         ...
         compileNLO
         ----------------------------------------------------------------------------------------------------------------------------

Perform the Integration
Create the executable TCHNLO_EXE_THISLIB in Linux/ directory
> ./MCatNLO.inputs.Integration (.)
Copy the PDF file in the run directory :
> cp /PDF/cteq6m.tbl ./cteq6m
Set the parameters for the complete integration:
> edit Integrationstep.Inputfile
Produce the Data Bases files:
> ./Linux/TCHNLO_EXE_THISLIB < Integrationstep.Inputfile
You should see the following produced TCHBase files :
> ls
-rw-r--r-- 1 lucotte atlas 124 Jul 27 17:41 TCHBase.integrals -rw-r--r-- 1 lucotte atlas 546K Jul 27 17:16 TCHBase_ain_bs.data -rw-r--r-- 1 lucotte atlas 546K Jul 27 17:24 TCHBase_aout_bs.data -rw-r--r-- 1 lucotte atlas 546K Jul 27 17:36 TCHBase_bin_bs.data -rw-r--r-- 1 lucotte atlas 546K Jul 27 17:41 TCHBase_bout_bs.data
Save the integration Results
- Create a directory with all the input files:
  > mkdir ./CTEQ6M_BASICS
  > cp TCHBase.integrals ./CTEQ6M_BASICS
  > cp TCHBase_ain_bs.data ./CTEQ6M_BASICS
  > cp TCHBase_bin_bs.data ./CTEQ6M_BASICS
  > cp TCHBase_aout.data ./CTEQ6M_BASICS
  > cp TCHBase_bout.data ./CTEQ6M_BASICS
  > cp cteq6m ./CTEQ6M_BASICS

EVENT GENERATION

Build the executable

cp MCatNLO.inputs.Integration MCatNLO.inputs.EventGeneration

where in this file you set

BASES=OFF

rm -Rf Linux/ : remove the old directory containing the executable

./MCatNLO.inputs.EventGeneration : creates a new executable Linux/TCHNLO_EXE_THISLIB

Run the new executable > cp Integrationstep.Inputfile EventGenerationstep.Inputfile where

 0 0       ! itmx1 itmx2

Run the executable

execute :
> ./Linux/TTbarNLO_EXE_THISLIB < EventGenerationstep_tch.Inputfile

which should lead to the files:
> TCHProd.events, containing the event hard interactions

Production of evgen by example

The DAT file must have this information in this order:

  'mcatnlo33.005503.tchannel_elec._0001.events' ! name of the event file to be processed
  5000                         ! number of events
  1                            ! 0->Herwig PDFs, 1 otherwise
 'P'  'P'                      ! hadron types
  7000.00 7000.00              ! beam momenta
  -2020                        ! -2000/10/20=all, s-ch, t-ch
 'HWLHAPDF'                    ! PDF group (1). It was MRS in the original ttMCinput file
  10000                        ! PDF id number (1). It was 105 in the original ttMCinput file
 'HWLHAPDF'                    ! PDF group (2). It was MRS in the original ttMCinput file
  10000                        ! PDF id number (2). It was 105 in the original ttMCinput file
  -.1000E+01                   ! Lambda_5, < 0 for default
 0.1750E+03 0.8042E+02         ! M_top M_W
 0.3200E+00 0.3200E+00 0.5000E+00 0.1550E+01 0.4950E+01 0.7500E+00 ! quark and gluon masses

Example of .events file

 0.1400E+05 0.1000E+01 0.1000E+01 0.1000E+01 0.1000E+01 --> CM energy, muR/mu0[NLO], muF/mu0[NLO], muR/mu0[MC], muF/mu0[MC]
   2020 --> 2000/10/20=all/s-ch/t-ch
 0.1750E+03 0.1700E+01 --> M_top, Gamma_top
 0.8000E+02 0.2124E+01 --> M_W, Gamma_W
  1 --> IL1 (1,2,3,7)
 0.3200E+00 0.3200E+00 0.5000E+00 0.1500E+01 0.5000E+01 0.7500E+00 --> quark and gluon masses
 P    P    --> colliding particles
 CTEQ         56 --> PDF group and id number
 0.2260E+00 MS --> Lambda_5, scheme
 P,M --> Format of v3.1 and higher
     5000
 408 14  7
   4   5  21   3 -11  12   5
 0.61569938E-02
 0.00000000E+00 0.00000000E+00 0.18530129E+03 0.15000000E+01 0.00000000E+00 0.00000000E+00 -.54942897E+02 0.50000000E+01 0.24720459E+00 0.61456197E+01 -.10869371E+02 0.75000000E+00 -.23923793E+01 0.16312596E+01 0.59242074E+01 0.50000000E+00 0.17846918E+02 0.97937069E+01 0.13278118E+02 0.51099890E-03 -.60528172E+02 -.54877020E+02 0.28142799E+02 0.00000000E+00 0.44826428E+02 0.37306434E+02 0.93882638E+02 0.50000000E+01
 408 15  7
 etc...

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