Week #167

7 – 9 April

A short week in terms of being at the institute. Until Monday including, I wrote quite a bit and finished my first chapter. I also started with an outline for the next chapter.

Back in Jülich, I’m preparing some plots I can show my professor on Wednesday for our bi-weekly meeting. This is a productive one with lots of ideas on how to proceed. Two main tasks I’ll look into in the next weeks: a probability ratio and a distance from a propagated track to a point.

First, I start with the probability ratio. When reconstructing, one often needs to originate particles from the same point in space, a so called vertex. A possibility in the analysis is to slightly alter the tracks of final state particles in order to have a common vertex. This process is called vertex fitting and yields a probability on how likely this altered track would be according to measurement uncertainties.

If more than one particle combination exists, one has to determine the likelihood of one combination over the other. My approach is to calculate the ratio of the probability for the current fit with the best and see, if this ratio is far off. That means, the current candidate has a much lower probability than the most likely one, thus is probably a wrongful combination.

I started to implement this by trying to get an ordered list of probabilities. It turns out to be more complicated than originally thought because of the interpreter I’m using which is not very capable when it comes to more specific C++ features. Therefore, I’m generating a class for this, but it doesn’t get finished this week.

Friday is off and the weekend full of big celebrations with friends and family, so not much writing 🙁

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