MicrOMEGAs:Introduction

Introduction: Micromegas v_1.3 for the MSSM

MicrOMEGAs is a code written in C for the calculation of the relic density in supersymmetry. It also calls some external FORTRAN functions. All annihilation processes as well as co-annihilation processes are calculated exactly through a supersymmetric version of CalcHEP. Co-annihilation processes include any type of slepton, squark, possible chargino or next to lightest neutralino as well as a gluino. By default the lightest neutralino is assumed to be the LSP, but the user can set any supersymmetric particle (not including Higgses!) to be the LSP, in particular a sneutrino. All in all we have included about 2800 processes not counting charge conjugate states. Care is taken to deal with resonances (in particular for the Higgs resonances) and thresholds.

The cross-sections extracted from CalcHEP are calculated exactly using loop-corrected masses and mixings as specified in the SUSY Les Houches Accord. The input parameters can be either the soft SUSY parameters in a general MSSM or the parameters of a SUGRA model specified at some high scale (GUT). In the latter case, a link with SuSpect, Softsusy, Spheno and Isajet allows to calculate the supersymmetric spectrum, Higgs masses, as well as mixing matrices. Higher-order corrections to Higgs couplings to quark pairs including QCD as well as some SUSY corrections
( ΔM_b( are implemented. Routines calculating the muon g-2, b → s γ and B_s→ μ μ are also included. In particular the b → s γ routine includes an improved NLO for the SM and the charged Higgs while the SUSY large tan(beta) effects beyond leading-order are included. This new version also provides cross-sections for any 2→ 2 process as well as partial decay widths for two-body final states in the MSSM allowing for easy simulation at colliders. We also provide a sample file to be used for scans over a set of parameters as in mSUGRA. It is also possible to view the contributions of different channels to the relic density.

System requirements: C compiler, Fortran compiler, 500 kb of disk space for download, a minimum of 20Mb as working space. Tested on: Dec Alpha, Silicon Graphics and Linux (Red Hat,Suse), SunOS and HP-UX .

Current version(August 2005) : micromegas_1.3.7
Removed a bug in the interface with non-universal SUGRA models for SLHA versions. No change in the SuSpect or Isajet interface(thanks to Joern Kersten)

micromegas_1.3.6 (June 2005)
changes and additions from 1.3.5
1. SuSpect 2.34 is implemented. data/s_cycle.res is updated for new SuSpect
2. More accurate treatment of SuSpect and Isajet error codes, sometimes a warning signal was treated as an error signal.
3. More accurate treatment of widths.: widths in s-channel included only near resonance (for example |2MLSP-mh|<2gammaH)

micromegas_1.3.5 (May 2005)
Only change from micromegas_1.3.4 is a correction of a small bug in B_s--> mu mu routine (Thanks to Michael Ramage)

(micromegas_1.3.4 (April 2005)

1. New SuSpect 2.33 is attached and is the default RGE code.

2. Bugs were removed from Fortran main sample programs (thanks to Werner Porod for pointing out the bugs).

3. Calchep/micromegas for Darwin (Unix on MAC) is now supported (thanks to Alexander Belyaev for his help).

4. The micro_make file was rebuilt:
a) micro_make clean
removes all generated files (de-installation);
b) automatically selects between make and gmake.

5. SLHA output updated: we now make a complete SLHA output which
contains all block and all parameters, not only the ones that are used in micrOMEGAs.

6. The SOFTSUSY interface is modified to force the package to calculate Am. If Am is not calculated by the RGE code, we use Am=Al (as in Isajet).

7. When several micromegas program run at the same time, we have replaced the LOCK file signal that the library is busy with the standard 'lockf' UNIX tool.

8. By default all the auxiliary and output files generated by RGE (in particular
suspect2.out) are removed. To save all files change the switch position with the command
delFiles(0)[call delFiles(0)] - to save files;
delFiles(1)[call delFiles(1)] - to restore default regime.

9. The bsg_nlo.c routine now reads MbPole, Mtp (pole) and alfSMZ from the main micrOMEGAs program. MbPole is calculated from the input value MbMb within micrOMEGAs.

10. Files from 'rge' and 'suspect' directories are moved to
'sources/'.

11. Bug removed in gluino coannihilation channels (Bug reported by Dan Hooper)

Previous version(January 2005) : micromegas_1.3.3

Changes and additions to micromegas_1.3.1 include

Bug removed in interface with SoftSUSY: correct reading of mixing angles for sfermions of the third generation.
Several bugs that led to a program crash were removed.
The default spectrum calculator code is suspect_2.31
In the function decay2 which calculates partial widths, the strong coupling is evaluated at the scale=mass of decaying particle.


New Extras:

1. The 'printMasses' routine now also displays the contents of the lightest neutralino:

~o1 = -0.825*bino +0.306*wino -0.454*higgsino1 +0.140*higgsino2

2. The 'masslimits_' function which checks the LEP limits on light SUSY particles sends a warning on the screen and returns a value that contains information about which sparticle masses do not satisfy the LEP limits.

RES= I_chargino + 2*( I_sneutrino-e +2*(I_sneutrino-mu +2*(I_sneutrino-tau+2*( I_selectron-R +2*(I_smuon-R +2*I_stau1)))))

where I_particle =0 if the LEP limit for this particle is satisfied and 1 otherwise.

3. New function writeLesH(char *fname) writes down MSSM parameters into a file in the Les Houches Accord format. Can be used for interface with PYTHIA 6.3
4. The function readInitFile(fname, LCon) used for calculations in EWSB models is split into two routines. First readEwsb(fileName) reads weak scale parameters from the file. Then suspectEwsbMSSM(LCon) or isajetEwsbMSSM(LCon) are used to evaluate masses and mixing angles. If LCon=0, loop corrections are implemented only to Higgs masses and mixing. Other masses and mixings are calculated at tree level.
5. The gaugino mass parameters MG1 and MG2 are read from the MSOFT block in the Les Houches file. These parameters are then used in the b->sgamma routine (bsg_nlo).
6. New functions for interfacing with spectrum calculator codes in the AMSB model:

extern int suspectAMSB(double am0,double m32,double stgbeta,double ssgnmu0,double cq, double cu, double cd, double cl, double ce, double chu, double chd);
extern int isajetAMSB(double am0,double m32,double tb,double sgn)
extern int softSusyAMSB(double am0,double m32,double tb,double sgn)
extern int sphenoAMSB(double am0,double m32,double tb,double sgn)

micromegas_1.3.1 : version(July 2003)
Changes to micromegas_1.3 included

Default RGE package is now suspect2.3
Default options in test programs are corrected.
Bug removed in Fortran version sugomg_f.f
Bug removed in ewsbInitFile() function
Data files omg.res and s_cycle.res corrected

Version(19 May 2003) : micromegas_1.3

Changes from version_1.1.1

Shortcomings to be included in next versions:

Although the program consists of about more 2800 processes (not counting charge conjugate related processes, etc), only tree-level processes are included. Missing are one-loop processes with 2 γ and 2 gluons in the final state. For the relic density these are negligible.