CalcHEP

Invariant mass peak

Asked by chahrazed

Hi,

I implemented a model in CalcHep which includes a heavy charged scalar with mass M = 835 GeV , after running this process :

 pp -> e^{+}mu^{+}e^{-} + E_miss , with S^{-} -> e^{-}nu_muon (S: intermediate charged particle)

I obtain the invariant mass distribution M( e^{-},nu_{muon} ) with two peaks, the first one at the value 835 GeV and the other at 30 GeV .
My question is ; How does one can explain the peak 30 GeV ??

Thank's.
Best

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Alexander Pukhov
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Alexander Pukhov (pukhov) said : 		#1

Send me your model, and energy of pp collision. It will we easy to explain/detect a problem when I'll see it in my computer.
Best
   Alexander Pukhov

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chahrazed (chahra-guella) said : 		#2

 I am working on a radiative neutrino model (similar to the Zee model), I attach the model files to your e-mail .
The energy of pp collision is taken at 8 TeV .

Best

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Best Alexander Pukhov (pukhov) said : 		#3

The second peak is caused by W propagator. The peak disappears if one sets addition cut M12 >200. So, then M12=sqrt((p1+p2)^2) close to MW, we have increase of cross section. S1+ propagator changed slow in this region.
If M12 small, them M(e,nm) is small too and should be about twice smaller that MW. But we have not resonance peak here.
Best
  Alexander Pukhov

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chahrazed (chahra-guella) said : 		#4

Thank's a lot of , your explication helped me to understand my process.

Best regards

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chahrazed (chahra-guella) said : 		#5

Thanks Alexander Pukhov, that solved my question.