CompHEP
CompHEP is a software
package for automatic computations in High Energy Physics from
Lagrangians to collision events or particle decays.
The CompHEP package consists of two parts, symbolic and numerical
programs. The symbolic part is written in the C programming language.
It produces C codes for squared matrix elements, and they are used in
the numerical calculation later on.
CompHEP is based on quantum theory of gauge fields. CompHEP
includes
the Standard Model Lagrangian in the unitarity and 't Hooft-Feynman
gauges and several MSSM models. Users can also create new physical
models, based on different Lagrangians, using a dedicated toool
(LanHEP).
CompHEP computes the LO cross sections and
distributions with several particles in the final state (up to 6-7). It
can take into account, if necessary, all QCD and EW diagrams, masses of
fermions and bosons and widths of unstable particles. Processes
computed by means of CompHEP can be interfaced to the Monte-Carlo
generators PYTHIA and HERWIG as new external processes.
Features include:
- Select a process by specifying
incoming and outgoing particles
-
Generate Feynman diagrams, display them, and create the corresponding
LATEX output
- Exclude some diagrams
- Generate and display squared Feynman
diagrams
- Calculate analytical expressions
corresponding to squared diagrams by using the fast built-in symbolic
calculator
- Save symbolic results corresponding
to the squared diagrams calculated in the Reduce and Mathematica codes
for further symbolic manipulations
- Generate the optimized C codes for
the squared matrix elements for further numerical calculations
- Launch the make program in order to
prepare the numerical part
The numerical part of CompHEP offers to:
-
Convolute the squared matrix
element with structure functions and beam spectra: built-in CTEQ and
LHAPDF parton distribution functions, the ISR and Beamstrahlung spectra
of electrons, the laser photon spectrum, and the Weizsaecker-Williams
photon structure functions are available
-
Modify physical parameters (total
energy, charges, particle masses, charges, etc.) involved in the process
-
Select an evaluation scale for the
QCD coupling constant and parton structure functions
-
Introduce various kinematic cuts.
Some cuts are built in and there is a special code to define more
involved cuts
-
Define a kinematic scheme (a phase
space parameterization) for effective Monte Carlo integration
-
Introduce a phase space mapping in
order to smooth sharp peaks of squared matrix elements and structure
functions
-
Perform Monte-Carlo phase space
integration by Vegas
-
Generate events
-
Display distributions of various
kinematic variables
-
Create graphical and LATEX outputs
for the histograms
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Last Updated Saturday, September 20 2008 @ 08:01 AM EDT
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