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What is SusyKit?

Essentially, SusyKit is a program that interfaces several packages that are useful for sampling and calculating the properties of parameter points in high-scale MSSM-based models.

The packages incorporated in SusyKit are:

• MultiNest provides an MPI-based sampling algorithm
• SOFTSUSY performs the RGE evolution and loop corrected mass calculations of the sparticles
• FeynHiggs computes masses, couplings, and decays in the Higgs sector to a far greater accuracy
• DarkSUSY includes routines for computing an extensive variety of physical observables related to dark matter experiments
• HiggsBounds tests against the 95% CL exclusion limits from collider searches in the Higgs sector
• SuperIso Relic is a C library that calculates a vast array of flavor physics observables, as well as the neutralino thermal relic density considering all tree-level coannihilation diagrams
• MicrOMEGAs computes the neutralino thermal relic density, direct and indirect detection rates for neutralino dark matter, along with the same for other dark matter models

SusyKit allows you to sample from the parameter space using prior distributions and a likelihood function provided to MultiNest, but also provides a generic MPI-based scanning system that draws purely random samples from prior distributions.

SusyKit also provides several useful command line utilities for investigating the parameter space: qpoint, constrain and qparse.

Installation

SusyKit is meant to be simple to install, but as you can probably expect from a package with inter-language libraries, it gets tricky. The basic instructions are as follows:

$ git clone [email protected]:freeboson/susykit.git
$ cd susykit
$ cmake .
$ make

That should fetch/unpack/compile/install all of the external libs and build the basic targets: qpoint, constrain and qparse.

On OS X, it's a bit tricky. To get the proper C++11 support, you have clang++ which is great. However, on OS X 10.8.5 and below, the default is to use libstdc++ and not libc++, and unfortunately cmake cannot figure that out for you. In this case, you will want to use GNU GCC via homebrew. Then you can run cmake this way:

$ CC=gcc-5 CXX=g++-5

Then, cmake will use GNU's gcc and g++. (The ones in /usr/bin are just symlinks to Apple LLVM.) Note that if you are on OS X 10.9 or newer you do not have to worry about this at all.

qpoint

The qpoint utility allows you to process a parameter point through the toolchain to compute the sparticle spectrum and physical observables. The output is not intended to be human readable, but instead should be piped into qparse. If you only want to see the SOFTSUSY SLHA output, you can use the -s or --slha flag. (Note, it will go to stderr, not stdout.) Currently the SLHA output will not include any of the observables, as in FLHA files. The help output for the utility is as follows:

General command:
qpoint [options] -- <m0> [MH1 MH2] [mq ml] [m3rd] <MG1 MG2 MG3 | mhf> <At Ab Atau | A0> <tb> <sgn(mu)>

The following options are available:
  -H, --help                 print this message
  -s, --slha                 output SLHA to stderr

Non-universality flags:
  -h, --higgs                seperate masses for Higgs fields, requires MH1 and MH2
  -g, --gaugino                 ... for gaugino fields, requires MG1, MG2, and MG3 instead of mhf
  -t, --trilinear               ... for trilinear couplings, requires At, Ab, and Atau instead of A0
  -3, --3rd-gen                 ... for 3rd gen sfermions, requires m3rd
  -f, --mq-ml                   ... for squarks and sleptons, requires mq and ml
  -F, --full-sugra           all masses and couplings are specified

Optional nuisance parameters:
      --alpha-s=VAL          alpha(strong), at scale MZ, by default:0.1184
      --alpha-em-inv=VAL     1/alpha(EM), at scale MZ, by default:127.933
      --mtop=VAL             top quark pole mass, by default:173.07
      --mbmb=VAL             running bottom quark mass mb(mb), by default:4.18

(Masses are specified in GeV.)

This lets you specify a sugra point with a few different types of boundary conditions. For example, for a plain mSUGRA scenario the format to follow would be:

qpoint [options] -- <m0> <mhf> <A0> <tan beta> <sgn(mu)>

For example, we could With the top quark mass set to 175 GeV, m0 = 200 GeV, mhf = 100 GeV, A0 = 0, tanβ = 15, sgn(μ) = 1:

qpoint --mtop=175 -- 200 100 0 15 1

As a more complicated example, we could also adjust the bottom quark mass, specify different masses for the 3rd generation sfermions, and for the gauginos, while requesting SLHA output as such:

qpoint -s3g --mtop=<mt> --mbmb=<mb> -- <m0> <m3rd> <MG1> <MG2> <MG3> <A0> <tb> <sgn(mu)>