Tutorial - Part 3: Testing the MC4BSM Model
You have learnt how to use CheckMATE to do model tests, both for well known pre-implemented models like the MSSM and for new models implemented in MG5_aMC@NLO via the UFO format. With this information, you know all there is to be known to test the MC4BSM model explained here. It contains additional heavy particles, some of which have colour charge (uv, uv~), some of which are like heavy electrons (ev, ev~), and two new scalars (phi1, phi2) with the lightest one being by construction stable, forming a possible dark matter candidate. In /home/checkmate/tutorial/part3 you find an example slha file for this model. Here, only uv, phi1 are kinematically accessible to make the start very simple.
Analyse this model point using CheckMATE. Beware the following points:
Again, the solution will tell you what your parameter card should look like.
- The Model is called MC4BSM_2012_UFO
- We test uv pair production as the only process.
- Out detector simulation needs to know that phi1 is an invisible particle, otherwise it will interpret it as a weird meson state which deposits hadronic energy. We can achieve this by setting the CheckMATE parameter InvisiblePIDs: 9000006. (Note that for the special case of the MSSM before, we did not need to do this as the detector simulation knows about the invisible neutralino).
- In the SLHA file, we set the widths of all new particles to AUTO. This will cause MG5_aMC@NLO to automatically calculate the decay widths and branching ratios of these particles. (This is just an information, it does not require any action from your side)
mg5process: p p > uv uv~
Run CheckMATE and see if the point is excluded or not. Convince yourself that the quoted best analysis is indeed good to look for our simplified model with only uv and phi1 being present
[Show Answer]The result might be affected by statistical fluctuations, but on average you should observe that the point is excluded, quoting a 2-jet signal region with highenergetic jets and a large amount of missing energy in analysis cms_1303_2985. In our scenario with only uv, phi1, we obviously have the final state uv uv~ -> u u phi1 phi1 which exactly corresponds to what this signal region is targetting. In principle, this corresponds to the MSSM with squarks directly decaying into quarks and the LSP. By playing with the masses, you would actually reproduce the well-known exclusion lines in the simplified squark-neutralino-scenario.
There is a plethora of things which you can test at this stage, using your combined knowledge from this and other MC4BSM tutorials. Here is just a few examples (without solutions):
- Use a different event generator which supports UFO, generate events and put these into CheckMATE. Check if and how the results change if you use a different event generator.
- Do a scan in a 2-parameter plance of the uv, phi1 masses and compare to the squark-neutralino limits.
- Add the phi2 particle to the spectrum (with mass between uv and phi1 and see what happens. Similarly, add the ev particle.
- Simultaneously test phi2 phi2 and ev ev~ pair production in one run. Check the numbers in the CheckMATE results/evaluation folder to see how the individual proceses contribute to the final result.
- Look out for a different UFO model, install it into MG5_aMC@NLO and try to analyse it with CheckMATE.