• Whizard

Whizard

WHIZARD (W, Higgs, Z and respective decays) is a program system designed for the efficient calculation of multi-particle scattering cross sections and simulated event samples. The most up to date version can be found at http://whizard.event-generator.org/. Anyhow, the version currently recommanded is that used to generate the SLAC standard model background sample and can be found at http://confluence.slac.stanford.edu/display/ilc/Standard+Model+Data+Samples.

Pre-Installations

Unfortunately WHIZARD depends on stdhep and O'Mega, which is using the programming language Objective Caml. So if you want to run Whizard on your machine you will first have to install these packages. You can get stdhep from http://cepa.fnal.gov/psm/stdhep/ and ocaml from http://caml.inria.fr/ocaml/index.en.html, respectively. O'Mega should be delivered with newer WHIZARD versions, but otherwise you can find it athttp://theorie.physik.uni-wuerzburg.de/~ohl/omega/. All of them deliver a README and a manual with them, so please have a look at them.

stdhep

This one is uncomplicated. Just follow the instructions in the README.

OCaml

Go into your ocaml directory and type

$ export OCAML='my path to OCaml'/ocaml-3.10.1
$ export PATH=$PATH:'my path to OCaml'/ocaml-3.10.1/bin
$ ./configure --prefix='my path to OCaml'
$ make world

With the --prefix option you can chose where to install ocaml. Now this package should also be fine.

Environment

Before installing WHIZARD, you have to set some path:

$ export F95=/opt/products/ifort/10.1/bin/ifort
$ export LIBS=-lg2c
$ export F77=/opt/products/ifort/10.1/bin/ifort

$ export OCAML=/data/nwattime/LDC_optimization/whizard/source/ocaml-3.10.1
$ export PATH=$PATH:$OCAML/bin

$ export STDHEP=/data/nwattime/LDC_optimization/whizard/stdhep/stdhep-5-06-01/lib/libstdhep.a
$ export FMCFIO=/data/nwattime/LDC_optimization/whizard/stdhep/stdhep-5-06-01/lib/libFmcfio.a

$ export CERNLIB_DIR=/cern/pro/lib

It is important to set the correct paths, otherwise your configuration will fail.

Adaption to the SLAC sample

Some pythia files and beam settings have been changed in the SLAC installation, to optimize whizard for the ILC. Thus, you should copy the a6f directory for fragmentation and guineapig directory for correct beam properties, as well as the whizard-src/user.f90 file from theSLAC page.

Installing Whizard

Now you can configure and afterward install WHIZARD

$ cd whizardDir
$ ./configure --prefix='my_path_to_WHIZARD' "USERLIBS=-L/my_path_to_a6f/a6f/lib/ -linclude"
$ make prg install

I had serios problems with

• make realclean and
• make distclean

they removed some .f95 files that were not restored by make, so don't use them! Better try

• make clean and
• make proclean

if you only changed the whizard.prc or whizard.in files.

Configuration

Whizard is using the CompHEP naming scheme. You can have a look at myWhizard/conf/models/SM.mdl, or MSSM.mdl to find out how to write your particles. Here is a short summary:

The configuration of whizard whould be done in the whizardDir/conf directory. Here you can modify the whizard.prc and whizard.in files to teach WHIZARD the process of interest. Note that WHIZARD expects any input files, e.g. SUSY Les Houche Accord files, to end with .in.

Physics Process

In whizard.prc you can chose which model and processes you are interested in

# The selected model
model MSSM_Grav

# Tag           In      Out                      Method Option
#====================================================================================
test1           e-,e+   A,GR,A,GR  omega  r: 3+4~neu1 && 5+6~neu1  //e+ e- -> 2 Neutralino1 -> 2 gamma + 2 Gravitino
test2           e1,E1   e1,E1                    chep

In case you want to have a look at a minimal supersymmetric standard model process, you have to chose O'Mega as method.

Beam Parameters

The whizard.in file contains informtaion about your beam, input files

 &process_input
 process_id = "test1"         //which process
 input_file = "SPheno"        //SUSY input with path to directory, should end with .in 
 cm_frame = T                      
 sqrts = 500                  //center of mass energy
 polarized_beams = T          //polarized beams is true
 structured_beams = T          
 luminosity = 500             //luminosity in fb-1
 beam_recoil = 

Polarisation is defined as left handed polarisation P_L / right handed polarisation P_R, e.g.

&beam_input
particle_name = 'e1'
polarization  = 0.9 0.1

This would result in an electron beam with 90% left, and 10% righthanded polarisation. Since these are defined as

P_R = (1 + P_e) / 2
P_L = (1 - p_e) / 2

the total electron polaristion P_e results in

P_e = 2*P_R - 1 = 1 - 2* P_L

For this example, we would get -80% electron polarisation.

Running Whizard

Once you have defined your process you can run compile WHIZARD

$ cd whizardDir
$ make clean
$ make proclean
$ make prg install

Now you can chage to the whizardDir/results directory, and run the executable whizard

$ cd ./results
$ ./whizard

The results will be displayed on screen and logged in whizard.test1.out.

Whizard does not know any non standard modell processes. Therefore, you have to teach it what to do. the process in test 1 will produce 2 neutralinos out of an electron positron collision, that decay into Gravitinos and photons. This option r is only available from whizard 1.51 on. MSSM_Grav will not be available before whizard 1.93, older versions do not know how to handle Gravitinos