Tutorial - Part 1: Our First Model Point Test

The Model

In this part of the tutorial you will use CheckMATE to test a given Supersymmetry model point. As the model, we will use the famous constrained Minimal Supersymmetric Standard Model (cMSSM): It is defined by five parameters (do not worry: you do not need to understand what they mean, they are just mentioned for completion):

• a universal scalar mass m0 (here: 2 TeV),
• a universal gaugino mass m12 (here: 350 GeV),
• a universal trlinear coupling A0 (here -4 TeV),
• the ratio of the two Higgs vacuum expectation values tanBeta = vu/vd (Here: 30) and
• the sign of the Higgsino mass parameter sgn(mu) (Here: +)

Supersymmetry predicts that each Standard Model particle p has a 'supersymmetric' partner particle ~p which differs in spin and mass. The gluon, as an example, has a partner called the gluino, which is a spin 1/2 particle (whereas the gluon is spin 0). The masses depend on the parameters of the model. The SUSY particles are usually heavy and - if they are produced - decay into lighter particles. However, a SUSY particle can (in most models) only decay into another SUSY particle and that makes the lightest particle automatically stable. This provides a nice dark matter candidate and produces large amounts of missing transverse energy - a signature which distinguishes it well from the Standard Model.

Using one of the many so-called spectrum generators on the market, one can find the masses and decays of all SUSY particle for the above model point. We have used SoftSUSY^[1] for the spectrum and SUSYHIT^[2] to find the decay tables. These tools use a common format to store their results, called SUSY Les-Houches Accord (slha).

Please have a quick look at the slha file that corresponds to the above model here.

In this first tutorial, we will try to find out whether this model point has been exluded by the 8 TeV LHC run or not.

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