Compute Breit-Wigner for particle decay

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Discussion Overview

The discussion revolves around the computation of the Breit-Wigner formula in the context of particle decay, specifically for a tau decay into a kaon, pion, and tau neutrino. Participants are exploring the mathematical aspects of the formula and its application in nonlinear fitting of data.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant inquires about the numerical computation of the Breit-Wigner formula for a specific particle decay and expresses confusion regarding the mathematical expression and the role of the imaginary unit.
  • A later reply suggests that the imaginary part of the Breit-Wigner expression disappears when squared, indicating a misunderstanding of the mathematical implications.
  • Another participant clarifies that the imaginary unit does not disappear but is squared in the denominator, contributing to the final result being real.
  • Further clarification is provided that the complex conjugate is involved, leading to a positive result when the imaginary units are multiplied.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the treatment of the imaginary unit in the Breit-Wigner formula, with differing interpretations of its role in the computation.

Contextual Notes

There is uncertainty regarding the mathematical steps involved in the computation of the Breit-Wigner formula, particularly in relation to the treatment of the imaginary unit and its implications for the final result.

mefistofeles
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Hey, I am just woondering if anyone here have computed (numerically) the Breit-Wigner for a particle decay. I have to do some nonlinear fitting of data but I need to compute this, any ideas?

My case is specific, and I am brand new to particle physics, it's for a tau decay into Kaon, pion and tau neutrino. The expression I have for the Breit-Wigner is posted in: http://mathbin.net/5566

I still don't understand the math beneath the expression. All I am asked is to compute it, what I am having trouble with is that i on the Breit-Wigner, I am not sure if that's the imaginary unit or something different, so if you know please help me compute this. Thanks for the attention.
 
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OK I gave it a second thought and I got it, that BW (for that decay) appears inside a function which is squared, so the imaginary part actually disappears, should have seen this before posting heh, sorry.
 
The I am doesn't disappear, but gets squared in the denominator.
 
OK, that's what I meant by "disappear", sorry the non-technical term. And you are right, it gets squared so that i^2 = -1 and the final result is real which corresponds to the "magnitude" of the complex number.
 
No. You take the complex conjugate so (i)(-i)=+1.
 

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