[G12] Missing mass plot for pKK -- Advice needed

[Mukesh Saini]

Hello all,

I am attaching a few plots and need help to understand the negative masses we get. I am using ClasEvent and bos2ntuple code to make my ntuples.

Code to make the plots:

root [30] ntp->Draw("sqrt( -mm_px**2 - mm_py**2 - mm_pz**2 + mm_t**2 ) -mm","","")
root [31] ntp->Draw("sqrt( -mm_px**2 - mm_py**2 - mm_pz**2 + mm_t**2 ) ","","")   
root [32] ntp->Draw("mm","","")                                                    

As you can see majority of mm is less than 0,hence I lose a lot of events when i make my cuts. The other way that I can calculate sqrt(E**2 - P**2) seems to give me the wrong answer too (All values positive even when I switch the signs on all terms inside the sqrt). I am sure this is some famous functionality that I am just unaware of. Please do let me know how to understand this and if needed fix this. 

Thanks,
Mukesh.

Graduate Student,
Florida State University.
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