carlomat

A general purpose program for automatic computation of leading order cross sections

by Karol Kołodziej


Institute of Physics, University of Silesia, Katowice, Poland; e-mail: karol.kolodziej@us.edu.pl


carlomat is a computer program for automatic computation of the lowest order cross sections of multiparticle reactions in the framework of the Standard Model. It can be used as the Monte Carlo generator of unweighted events as well. The program has been written in Fortran 90/95 .

carlomat_2.0: has built-in interfaces to parton density functions, generates a single phase space parametrization for the Feynman diagrams of the same topology; improved color matrix computation; the Cabibbo-Kobayashi-Maskawa mixing in the quark sector included; the effective models including scalar electrodynamics, the Wtb interaction with operators of dimension up to 5 and a general top-higgs coupling implemented; some minor modifications and several bugs in the program corrected.

carlomat_3.0 is dedicated to the description of processes of electron-positron annihilation to hadrons at low centre of mass energies.

carlomat_3.1 a new version of the program which, among others, include a possibility of taking into account either the initial or final state radiation separately, or both at a time, and a possibility of inclusion of the electromagnetic charged pion form factor for processes with charged pion pairs.

carlomat_4.0 a new version of the program which substantially improves efficiency of the phase space integration by automatic inclusion of parameterizations which map away the t-channel poles and peaks due to soft and collinear photon or gluon emission. The quadruple precision versions of the routines for computation of the helicity amplitudes and phase-space parameterizations have been written and calls to them implemented in the code generation part of the program. This allows to better control numerical stability of the Monte Carlo programs generated. A new option of generating s-channel kinematics has been added which takes into account peaks due to Feynman propagators of intermediate bosons which decay into on shell final state particles, or of the top quark. It speeds up both the compilation and execution time of the Monte Carlo programs with respect to the kinematics based on topologies of the Feynman diagrams used in versions 2 and 3 of {\tt carlomat}. To further speed up the execution time, the main routine of the Monte Carlo program has been supplemented with the Message Passing Interface which allows to run the program parallelly on several processors.

carlomat_4.4 a modification of the program which allows to incorporate the multichannel MC integration routine generated with the program PSGen.


Please report bugs to Karol Kolodziej