MSSM (and extensions) Lagrangian for CompHEP package
Introduction
We present here the files necessary for SUSY processes
calculation by
CompHEP package. The installation instructions are in the
README file .
Start CompHEP and new models will appear in menu.
CompHEP/SUSY models were created my means
of LanHEP package. Last versions
of LanHEP (2.4, 2.5) include input files to generate MSSM and
some extensions.
Sources
The LanHEP input files to generate MSSM and its extensions come
within LanHEP distributions. One can use ready models listed below:
Basic MSSM contains the models number 5 and 6 (unitary and Feynman gauge
fixing), extensions are numbers 7-8. If you install several extensions,
you should unpack the archive in a temporary directory and rename the
files to the next free number (e.g. vars8.mdl -> vars9.mdl, func8.mdl ->
func9.mdl, etc). Then copy renamed files to the 'models' subdirectory of
the CompHEP user directory.
SUSY Les Houches Accord (SLHA) interface
To use SLHA in CompHEP/SUSY, one has to update usrlib.a (or libmssm.a
in newer CompHEP versions). Compile new sugrac.c file
and put it into the library (ar -r usrlib.a sugrac.o). Files
sugraf.f and sugrag.f are not necessary in this library. Now
CompHEP will write the file named slhaInput with RGE input parameters
(M0, M1/2, tb, etc) in SLHA format, then it executes the script
named slhaScript, and finally reads soft masses and trilinear
couplings from the file named slhaOutput, produced by script.
The script is searched first in the current directory (usually results/)
and then in the parent directory (usally where symbolic part of CompHEP
is launched). Generally slhaScript may be a compiled executable file rather
than script.
There are examples of scripts for some packages (you should
download necessary package independently, and edit the script
to set the directory where the package is):
ISASUSY: there is a temporal solution to use ISASUSY with
SLHA version of CompHEP/SUSY. To make "script" for this case,
compile 3 files: sugraf.f ,
sugrag.f , isaslha.c
together with ISAJET library. Or download the precompiled executable file
for Linux slhaScript.isa
Rename the required file to slhaScript, do not forget to set
execution permission (chmod +x).
NMSSM for CompHEP
NMSSM for CompHEP can be downloaded here .
File nmssm2.c in the archive should be added to library
usrlib.a (libmssmlib.a in newer CompHEP versions). You should download
the NMHDECAY package and create SLHA (it is default currently) executable,
name it nmhdecay and
place it to the directory where numerical CompHEP is launched (usually
results/ ). Remember that NMHDECAY also require the directory
LEPCON to be nearby.
New parameters in the model
are hL for lambda and hK for kappa, hLs and hKs are corresponding soft
parameters. Notation for third fermion and sfermion parameters is slightly changed:
everywhere top->t, bot->b, tau->l. See further details in the paper
on NMSSM in micrOMEGAs (to appear in hep-ph in May 2005). The present model
has mixing of d,s quarks by Cabbibo angle while the model in micrOMEGAs
has diagonal CKM.
Updates history
April 17, 1998. Signs corrected in neutralino-chargino sector
and in Yukawa terms.
July 18, 1998. Signs corrected in the 2 gluons + 2 squarks
(4-legs) vertices.
November 14, 1998. Signs corrected in soft SUSY-breaking terms.
March 10, 1999 - new MSSM for CompHEP
with R-parity violation, gravitino and NMSSM options.
March 14, 1999 - Vertices (neutrino, electron, charged Higgs)
and (chargino, neutrino, selectron) are corrected (extra factor
1/2 was removed; it was inserted by mistake at November 1998).
R-parity violation and gravitino models
compared with SUSYGEN.
May 16, 1999 - CompHEP model files updated to fit the CompHEP
version 3.3.20 ('Sqrt()' replaced by 'sqrt()'). Source code
for MSSM extensions is available.
June 8, 2000 - vertices (neutralino_i, neutralino_i, Z)
are corrected (sign changed). Sparticle mixing effects in the
2nd generation are taken into account.
December 20, 2001 - CompHEP/SUSY models are in the new representation.
April 29, 2003 - updated user library (FeyHiggsFast 1.2.2).
January 28, 2005 - SLHA interface.
May 10, 2005 - NMSSM.
Mar 31, 2008 - bug fixed in 4-squark and 4-slepton vertices:
1. wrong interference sign of FF terms is fixed, 4-scalar vertices
with Higgs bosons were (and are) correct. LanHEP 2.5 has to be
used to generate correct model; 2. Wrong interference sign
for 4 squarks vertices coming from DD terms proportional to
alpha_s is fixed. File susy_dd.mdl is corrected. The input
files to generate MSSM come within LanHEP 2.5.0 (see LanHEP page).