MM or M in fun with LoKi functors

[saschastahl]

Hi all,
I think this lesson should not mention MM. It should use M. When the OfflineVertexFitter was used M and MM were the same. Since we use the LoKi::VertexFitter they are slightly different. MM is a combination of the daughter 4-momenta, while M is the result of the vertex fit and should be slightly better than MM.

[alexpearce]

I agree that M is ‘better’, and its what analysts should almost always use. Still, part of me wants to keep a mention of M in the lesson (or some lesson) as students invariably asked what the difference is.

Maybe the best solution is to add a callout box somewhere, explaining the difference and saying which one should be used.

[betatim]

Some discussion of this (and work done to fix it): #148

[saschastahl]

I knew this was discussed before :). My reaction was triggered by seeing _MM in a presentation. A callout box might be the best solution.

[betatim]

To use the search box, you have.

[saschastahl]

Not sure we want to replace mm with m :)